THE ANATOMY OF PACHYDERMIA LAEVIS (ARCHAEOGASTROPODA: 'PELTOSPIRIDAE')

The anatomy of Pachydermia laevis Warén & Bouchet,1989 is investigated. It is a deep-sea gastropod and restrictedto hydrothermal vents of the East Pacific Rise. Its anatomyresembles that of Melanodrymia aurantiaca Hickman, 1984 (Melanodrymiidae)in most respects, except that its gonopericardial duct opensinto the renopericardial duct, not into the peri-cardial chamber,and that it lacks a copulatory organ. Examination of M. aurantiacamain confirms earlier work. The two species have a cerebralbuccal connective fused with the cerebral ganglion (not freefrom it), a synapomorphy that has not been described for anyother archaeogastropod. The investigation suggests that Melanodrymiaand Pachydermia are closely related and together with Cyathermiidaeand Neomphalidae form a monophyletic group within the Neomphalina.No evidence was found to support earlier speculations aboutclose relations of Neomphalina to Viviparoidea. (Received 10 January 1996; accepted 3 April 1997)     

THE ANATOMY AND RELATIONSHIPS OF ELACHISINA DALL (GASTROPODA: RISSOACEA)

Species of Elachisina are marine and extend from the Caribbeanand western North and Central America to the Philippines, Hawaiiand New Zealand. The anatomy and other morphological featuresof Elachisina ( = Microdocluis) floridana (Rehder) from theFlorida Keys are described and compared with rissoacean familiesjudged to be most closely allied. This species has a uniquecombination of characters which do not correspond to those character-setsused to define any known rissoacean family. Important featuresinclude a metapodial as well as pallial tentacles, a wide ctenidiumwith low, triangular filaments, an osphradium which is shortrelative to the ctenidium, an S-shaped loop of the intestinewhich extends into the pallial roof, long dorsal folds in themidoesophagus, a rather loosely organised nervous system, anopen prostate gland from which the pallial vas deferens exitsat its anterior extremity, glandular lobes on the penis, a non-glandularfold on the right side of the ventral channel of the capsulegland and a fold on the left side in the posterior end of thechannel, a pair of seminal receptacles lying between the albumenand capsule glands, a bursa which lies alongside the capsulegland and opens posteriorly to the ventral channel and a U-shaped,expanded section of the oviduct proximal to the albumen glandand seminal receptacles. This combination of characters is consideredto be sufficiently distinct to arrant the erection of a newfamily-level taxon to accommodate the small group of speciesjudged to be congeneric with E. floridana. The Elachisinidaeappears to be most closely related to the Rissoidae, Iravadiidaeand Hydrobiidae. (Received 19 October 1983;     

COMPARATIVE ANATOMY OF THE PETIOLE AND INFRAGENERIC RELATIONSHIPS IN JATROPHA (EUPHORBIACEAE)

Anatomical features of the petiole in several species of Jatropha L. (Euphorbiaceae) are presented as evidence in support of infrageneric relationships. A trilacunar 3-trace nodal pattern is typical for the genus. The vascular supply to the stipules is derived from the branching of the two peripheral leaf traces. The number of vascular bundles range from 11 through 9, 7, 5 and 3, and occur in a ring, as free traces, a medullated cylinder, or as U-shaped free traces. The reduction from nine to three bundles is correlated with the gross morphological features while 11, which occurs only in the section Peltatae (Pax) Dehgan & Webster, presents an increase. Reduction in the number of petiolar traces follows the evolutionary advancement of various taxa. This reduction in traces corresponds with south-north distribution of the species and consequential adaptation to colder and more arid climates in Central America and Africa. Smaller leaves, fewer primary veins and fewer vascular traces have resulted as a response to reduced need for water. Presence of dorsal (super-numerary) bundles which supply the petiolar glands in subgenus Jatropha (= Adenoropium Pax) is considered significant, since African taxa of the section (subsection Pubescentes Pax) have retained these bundles despite the loss of petiolar glands. The latter glands are prominent in the South American and Indian species. Sectional lines in the genus can, therefore, be drawn generally on the basis of numerical constancy and relative uniformity in the arrangement of petiolar traces. The continuity of vascular bundles from the stem into the petiole and variations of bundle arrangements are depicted in three-dimensional drawings.     

THE ANATOMY AND RELATIONSHIPS OF A MARINE VALVATOIDEAN (GASTROPODA: HETEROBRANCHIA)

The anatomy of Cornirostra (new genus) pellucida (Laseron),a marine Indo-West Pacific gastropod, is described and is shownto be similar to that of the northern hemisphere, freshwaterValvatidae. There are, however, several differences betweenCornirostra and valvatids, notably in details of the anatomyof the reproductive system, the morphology of the head-foot,the spawn and in radular characters that warrant family-levelseparation for Cornirostra. Tomura bicaudata (Pilsbry and McGinty) from Florida is alsoa member of the family. (Received 9 September 1989; accepted 30 December 1989)     

WOOD ANATOMY AND RELATIONSHIPS OF LACTORIDACEAE

Mature wood of Lactoris, not previously available for study, reveals ten distinctive characters: vessels with simple perforation plates; vessels in pore multiples; vessel-to-axial parenchyma pits scalariform or transitional, vessel-to-vessel pits alternate; fiber-tracheids with vestigial pits; fiber-tracheids, vessels, and axial parenchyma storied; axial parenchyma vasicentric scanty; axial parenchyma either not subdivided or, if subdivided, with thin nonlignified walls between the cells (like the septa in septate fibers); rays wide and tall, little altered during ontogeny; ray cells upright; and ray cells taller adjacent to fascicular areas. All of these features occur in woods of Piper and other Piperaceae. The systematic position of Lactoris is therefore reassessed. Evidence available to date is consonant with placement of Lactoridaceae in Piperales, in which it would be more primitive than Piperaceae or Saururaceae. Features cited as evidence for alternative placements of Lactoridaceae are reviewed.     

THE ANATOMY AND RELATIONSHIPS OF HYDROCOCCUS BRAZIERI (T. WOODS): Mollusca: Gastropoda: Rissoacea

Hydrococcus brazieri is an abundant, small gastropod which livesin brackish habitats on intertidal mud flats along the westernand southern coasts of Australia. It is typical of the Rissoaceain basic morphology but has a unique combination of charactersthat suggest it should be placed in a separate family, the HydrococcidaeThiele, 1928. The final assessment of the relationships of Hydrococcusmust, however, await more detailed information about relatedfamilies. The distinctive characters of Hydrococcus includea multispiral operculum with a central nucleus, a long, posteriorpallial tentacle with a short tentacle at its base, no metapodialtentacle, a penis bearing two accessory lobes, a bursa copulatrixwhich opens directly into the mantle cavity independently ofthe oviduct opening and rather long connectives between boththe pleural and oesophageal ganglia. There is no ctenidium butfolds on the pallial roof probably have a respiratory function. Hydrococcus graniformis Thiele and Ampullarina minuta T. Woodsare shown to be synonyms of Rissoina brazieri T. Woods. A clinebetween the forms typical of brazieri and graniformis is demonstrated. (Received 20 November 1980;     

THE SYSTEMATICS AND ANATOMY OF GONGYLOCARPUS (ONAGRACEAE)

The unique fruiting structures of the closely related, principally Mexican, monotypic genera Gongylocarpus and Burragea (Onagraceae) compelled a detailed anatomical and cytological investigation of these plants which led to the conclusion that they should be included in a single genus, Gongylocarpus. Gongylocarpus fruticulosus (Burragea), endemic to two adjacent islands off the west coast of Baja California, is divided into two subspecies, subsp. fruticulosus and subsp. glaber. The vegetative and floral anatomy, including wood anatomy, of both species is described. The fruits of these two species grow into the stem by meristematic activity during the course of ontogeny, the ovaries in the mature flower being superficial and sessile in the leaf axil. There is no pedicel associated with the flower, but only a branch gap. Meristematic tissue at the base of the locules divides rapidly at a relatively late ontogenetic stage, the ovaries growing downward into the stem and crushing the pith. The mature, heavily sclerenchymatous fruits are located wholly within the stem, and in G. fruticulosus they are aggregated into long chains. Both species have a gametic chromosome number of n = 11, a characteristic otherwise unknown in the tribe Onagreae but shared with other generalized groups in the family. Taken together with other features, this suggests a primitive position within the tribe for Gongylocarpus.     

THE MORPHOLOGY AND RELATIONSHIPS OF DALECHAMPIA SCANDENS (EUPHORBIACEAE)

The circumtropical but preponderantly American genus Dalechampia, comprising nearly 100 species of twining vines (or rarely subshrubs), is strikingly isolated within the Euphorbiaceae because of its distinctive bibracteate inflorescences. There has been considerable taxonomic controversy with regard to the relationships of the genus, and it has been suggested that Dalechampia is allied to the tribe Euphorbieae because of a supposed analogy between its inflorescence and the cyathium in the Euphorbieae. Field and laboratory investigations of the common American species D. scandens, together with a comparative survey of related species, have thrown some light on these problems. The Dalechampia inflorescence seems best interpreted as consisting of a terminal staminate pleiochasium (with part of the lateral branches transformed for nectar production), juxtaposed to a 3-flowered pistillate cyme. The lips of the conspicuous bilabiate involucre are formed by the hypertrophied bracts which subtend the staminate and pistillate cymes. The bisexual inflorescences appear to be distinctly proterogynous, rather than proterandrous, as has been previously suggested. The configuration of the inflorescence—a bilaterally symmetrical pseudanthium—suggests adaptation for crosspollination, but the closing movement of the bracts makes self-pollination probable in the absence of visits by pollinators. The similarity of the Dalechampia inflorescence to the cyathium of the Euphorbieae appears to be entirely superficial, and both reproductive and vegetative data suggest that Dalechampia is related to taxa of tribe Plukenetieae.     

ANATOMY AND RELATIONSHIPS OF SOME DEVONIAN PROGYMNOSPERMS FROM NEW YORK

New specimens of Triloboxylon ashlandicum Matten and Banks (1966) show additional features of the anatomy and morphology of the plant. The primary xylem has strands of parenchyma associated with trace formation. Secondary xylem and phloem are described for the first time. The outer cortex, previously unknown, contains hypodermal fiber strands. The ultimate appendages are much divided and planated. Specimens of Aneurophyton hallii (Arnold, 1940) were reexamined and newly prepared. They are transferred to the genus Triloboxylon as T. hallii. Triloboxylon is transferred from Pteropsida-Incertae Sedis to the Aneurophytales. New information on the morphology and anatomy of Telraxylopteris is presented and its identity to Sphenoxylon is supported.     

REPRODUCTIVE BIOLOGY OF WEEDY AND CULTIVATED MIRABILIS (NYCTAGINACEAE)

The reproductive biology of Mirabilis nyctaginea (Michx.) MacM. contributes to the plant's success as a weed and invader of disturbed habitats whereas that of M. Jalapa L. reflects its success as a cultivar. Plants of M. nyctaginea flowering in early summer produce chasmogamous flowers whereas plants flowering in late summer produce cleistogamous flowers. Plants of both species are self-compatible and flower behavior contributes to self-pollination. The flowers open late in the afternoon and close late the following morning. In M. nyctaginea flowers are effectively pollinated by bees both in the afternoon and morning, and during the night moths are effective pollinators. Mirabilis Jalapa is self-pollinating. Anther closure during rain showers, a result of water droplets falling into open anthers, minimizes pollen loss and is highly adaptive. The reproductive biology of M. nyctaginea and M. Jalapa is contrasted with that of the obligate outcrossing species M. multiflora (Torr.) Gray and M. froebelii (Behr) Greene.     

ONTOGENY AND ANATOMY OF THE FLOWER OF LIMNOCHARIS FLAVA (BUTOMACEAE)

The flowers of Limnocharis flava (L.) Buch. are borne in an indeterminate umbel and each consists of three sepals, three yellow petals, and about 18 carpels surrounded by numerous stamens and staminodia. The androecium is centrifugally developed, and the last-formed members are staminodial; it is supplied by branching vascular systems. Carpels arise almost simultaneously, and a prominent residual floral apex remains. The carpels are partially conduplicately closed and are also primitive in possessing laminar placentation and in lacking differentiation of a style. The gynoecium is essentially apocarpous, but there are slight fusions of adjacent carpels near their ventral margins where they are attached to the receptacle. It is suggested that the Limnocharis flower is the most primitive in the family.     

THE ECOLOGY OF THE HONG KONG LIMPETS CELLANA GRATA (GOULD, 1859) AND PATELLOIDA PYGMAEA(DUNKER, 1860): DISTRIBUTION AND POPULATION DYNAMICS

Cellana grata is a high-zoned, exposed-shore limpet with a lifespanof 3 years. Patclloida pygmaeais a low-zoned, sheltered-shorelimpet with a lifespan of I year. C. grata migrates up-shorein winter, but occurs lower on the shore in summer. This migrationis synchronized with variations in algal availability high onthe shore; such variations are, however, themselves relatedto seasonal changes in wave height. P. pygmaea is restrictedto the low shore, year round. The movements upwards in winterand downwards in summer are still evident. Algal species richnessincreased from September to reach a peak between December andMarch, and to abruptly diminish between May and June. The encrustingalgae Brachytrichia maculans, Hildenbrandia prototypus, Lithothamnionsp. and Ralfsia vcrrucosa were present year round. The timingof juvenile recruitment of C. grata and P. pygmaea was fromOctober to July and February to October, respectively. Temperaturemay be important in enhancing juvenile survival by affectingthe seasonal pattern of algal occurrence on the shore. Seasonalfluctuations in the rate of growth were recorded for both specieswith the time of fastest growth of C. grata and P. pygmaea occurringbetween October and March and September and February, respectively.Mortality of both species occurred mainly in summer. Summerheat, predation and intra-specific competition for food appearto be the major causes of death. (Received 1 December 1992; accepted 5 May 1993)     

HEARTWOOD FLAVONOIDS AND THE INFRAGENERIC RELATIONSHIPS OF RHUS (ANACARDIACEAE)

Heartwood flavonoids of 23 taxa of Rhus L. were surveyed in order to assess infrageneric relationships and classification. Fourteen flavonoids and two coumarins were detected in the heartwood extracts. All taxa were characterized by a flavonoid complement consisting of eight 5-deoxyflavonoids involving several aglycone classes (e.g., flavonols, flavones, aurones, chalcones and dihydroflavonols) and the aurone rengasin. None of the 5-hydroxyl analogs of the 5-deoxyflavonoids were detected in the heartwood extracts. Infraspecific flavonoid patterns were uniform in different populations, although the presence of 3′,4′-dihydroxyflavone 4′-O-β-glucoside varied in some taxa. Taxa of Rhus subgenus Rhus consistently differed from all taxa of Rhus subgenus Lobadium in lacking glycosides of fisetin, butein and 3′,4′-dihydroxyflavone. The major evolutionary trend in the heartwood flavonoids of Rhus appears to be accumulation of simple mono- or diglucosides. Data from heartwood flavonoids suggest that Rhus be treated as consisting of two subgenera (Rhus and Lobadium) and that subgenus Lobadium be divided into three sections.     

THE EFFECT OF ENVIRONMENTAL VARIABLES ON THE OXYGEN CONSUMPTION OF THE PROTOBRANCH BIVALVE NUCULA TURGIDA (LECKENBY AND MARSHALL)

The oxygen consumption of the protobranch bivalve Nucula turgidawas measured in relation to size and to variation in temperatureand ambient oxygen tension. The slope of the line relating logsize and log oxygen uptake varied from 0.539 to 0.884 over therange 5°C to 40°C in summer – conditioned (S)animals but for winter – conditioned (W) animals the slopevaried from 0.561 to 0.762 over the range 5°C to 15°Conly; from 20°C to 35°C the values for the slope fellfrom 0.298 to 0.092. There was evidence of reverse acclimation,since the absolute rate of oxygen consumption was greater inS animals than in W over the temperature range studied. Thelethal limit for both groups appeared to be between 30°Cand 35°C. At all temperatures (5°C–25°C) N. turgida wasfound to be a near complete oxyconformer with b₂ x 10³ valuesranging from +0.0754 to –0.0234. The responses to temperature differ little from those of eulamellibranchbivalves, but the lack of ability to oxyregulate does demonstratea difference which may be linked to the different gill structure. (Received 13 January 1983;     

GENERIC RELATIONSHIPS OF DECASCHISTIA (MALVACEAE) AND THE DESCRIPTION OF A NEW TRIBE,DECASCHISTIEAE

The Asiatic genus Decaschistia has traditionally been placed in the tribe Hibisceae, but it is shown that this genus has a combination of characters that does not permit it to be accommodated either in the Hibisceae or in any other tribe of the Malvaceae. A new tribe, the Decaschistieae Fryx., is therefore described and distinguished from the other four tribes currently accepted in the Malvaceae.     

奇异球蛛的核型分析（蜘蛛目：球蛛科）

第1次报道奇异球蛛的核型,包括染色体数目、形态结构、性染色体组成。实验结果表明奇异球蛛染色体数目是:雄体细胞为2n=21,雌体细胞2n=22,性决定机制为XO系统,X染色体为最短的1个(对)。对C-带标本分析表明:所有染色体均为端或亚端丝粒,各染色体有其识别特点。