THE LAKE ST. LUCIA SYSTEM—A RESEARCH ASSESSMENT

SUMMARY

This paper assesses the research undertaken at Lake St. Lucia over the past 25 years based on over 300 documents from that period. Trends related to both time and subject matter are evident, and these are considered in relation to the gaps in our current knowledge concerning the system.

A feature evident throughout the period under consideration is that the major portion of documented material available relates to reports and contributions to workshops (77%) with only 23% from scientific publications. Contributions by these two sources to the subject group being considered for St. Lucia are markedly different with research publications dominating the biological field and reports dominating in physical aspects, catchment characteristics, man's activities, management, dredging and hydrological modelling. However, some 55% of all unpublished data related to reviews or assessments of the state of research on St. Lucia.

The importance of the scientific publications group as an indicator of the state of research into the system is considered in the light of an apparent decline in the number of completed projects being published. It is also considered in the light of the recent establishment of a co-ordinated Lake St. Lucia Research Programme, which may provide the impetus for a more concentrated and directed research effort on the Lake System.     

YANGTZEDONTA——A PROBLEMATIC BIVALVIA FROM THE MEISHUCUNIAN STAGE, CHINA

During the last 20 years, as in studies of other molluscan groups, new progress has been made in researches on the Cambrian bivalvia with the discovery of some new genera and species such as Fordilla siberica Krasilova (1977) from the Lower Cambrian Atdabanian Stage of the Siberian Platform, USSR, Pojetaia rvnnegari Jell (1980) from the Lower Cambrian Parara Limestone Bed of Southern Australia and Tuarangia paparua Mackinnon (1982) from the Middle Cambrian Tasman Formation of New Zealand. In China, although there were also reports on the Cambrian fossil bivalves in the past, it is still difficult to determine the taxonomic position of these fossils because in these described specimens no definite hinge structures can be seen, nor exist any reliable indications of muscle scars. In 1981, while identifying some molluscan fossils from the Lower Cambrian Xinji Formation in Luonan, Shaanxi, the writer discovered the geuns Po]etaia associated with Anabcrella Vostokova, 1962 and Pelagiellids (Yu, 1983: Yu, Xu e     

CIRCADIAN RHYTHMS IN HEALTHY AGING—EFFECTS DOWNSTREAM FROM THE PACEMAKER

Using both previously published findings and entirely new data, we present evidence in support of the argument that the circadian dysfunction of advancing age in the healthy human is primarily one of failing to transduce the circadian signal from the circadian timing system (CTS) to rhythms “downstream” from the pacemaker rather than one of failing to generate the circadian signal itself. Two downstream rhythms are considered: subjective alertness and objective performance. For subjective alertness, we show that in both normal nychthemeral (24h routine, sleeping at night) and unmasking (36h of constant wakeful bed rest) conditions, advancing age, especially in men, leads to flattening of subjective alertness rhythms, even when circadian temperature rhythms are relatively robust. For objective performance, an unmasking experiment involving manual dexterity, visual search, and visual vigilance tasks was used to demonstrate that the relationship between temperature and performance is strong in the young, but not in older subjects (and especially not in older men). (Chronobiology International, 17(3), 355–368, 2000)     

THE PLIOCENE MICROMAMMALIAN FAUNA FROM JINGLE, SHANXI——A DISCUSSION OF THE AGE OF JINGLE RED CLAY

<正> The Cenozoic deposits of Jingle area was first explored by Teilhard de Chardin & Young in 1929, and six species of mammals: Hipparion houfenense, Gazella blacki Antilospira licenti, Elephas sp., Cervus sp., and Rhinocerotidae gen. indet, were found from the Red Clay in Loc. 1 (Hefeng). Based on the Jingle Fauna, Teilhard de Chardin & Young concluded that the fossil-bearing layer was situated between the typical Hipparion richthofeni Red Clay (Pontian) and the Sanmenian deposits (Polycene) (Teilhard de Chardin & Young, 1930, 1931) and called it "Upper Pontian". Since then, Jingle Formation (or Jingle Red Clay) has been widely used in the stratigraphic generalization of North China (Pei et al., 1963) although its definition and age assignment have never been cleared up. "Jinglean" was put into use for the first time as a stage name by Li et al. (1984, in Chinese) to represent Early Pliocene tentatively: "It may be equivalent to Early Pliocene, more plausibly, it is later ...... Jinglean was temporarily used here to represent Early Pliocene by tradition." In order to make clear the age of Jingle Red Clay and enrich the Hefeng Fauna, a field survey was made in the Summer of 1986 by Chen Xiaofeng and the author. An assemblage of fossil micromammals was unearthed by means of wet-sieving techniques. About 1 ton of sediments from Hefeng (Loc. 86007, or Loc. 1) and Xiagaoai (Loc. 86008, or Loc. 2) in Jingle county (see fig. 1), yielded over 1000 specimens of small mammals. The specimens are from four layers (see table 1), and the present paper only deals with the micromammals from the sand layer and the Red Clay at Hefeng (fig. 2).     

THE REMOVAL OF STONES FROM LOW IN THE URETER—A Report on an Improved Method

Extraction of stones from the lower part of the ureter can be facilitated by use of a long filiform which permits the attachment and introduction of dilating Phillips catheters of increasing caliber and of various stone extractors. The filiform must be left in place, with the tip superior to the stone, until the ureter has been successfully dilated, the stone extracted and a drainage catheter inserted. The filiform serves to guide the instruments up the ureter.Smooth muscle relaxation, or “tone paralysis,” is achieved by leaving each dilating catheter in the ureter for at least ten minutes.A combination of spinal and local anesthesia is used, and this contributes further to the desired ureteral relaxation. This simple method was used successfully in 34 of 35 consecutive cases to remove a stone in the lower part of the ureter.     

A NEW SUBSPECIES OF THE SILVER PHEASANT FROM SZECHWAN, CHINA——LOPHUA NYCTHEMERA OMEIENSIS

The occurrence of silver pheasants in Szechwan has aroused much interest and con-cern. Specimens previously collected there by Tang Jui-chang and others have recentlybeen examined and found to belong to a new subspecies, which we propose to nameas:     

JINKENITES——A STRANGE FOSSIL FROM EARLIEST CAMBRIAN IN W. HUBEI

A strange fossil described and illustrated in the present paper was collected by the writer in 1978 from the Huangshandong Member of the Lower Cambrian Tongying Formation in western Hubei. The material was preserved in greyish brown phosphoritic dolomites in association with elements of the Yangtze Micromolluscan Fauna, such as Tchangsichiton notabilus Yu and Sinuconus clypeus, Yu of Class Polyplacophora; Yangtzemerisma rarum Yu and Y.? cancellatum Yu of Class Merismoconchia; Yangtzeconus priscus Yu, Huangshandongoconus pileus Yu, Obtusoconus paucicostatus Yu, O. rostriptutea (Qian) and Spatuloconus rudis Yu of Class Monoplacophora; Bemella simplex Yu, Latouchlla of. memmorabilis Missarzhevsky, L. sanxiaesis Yu and L. lauta Yu of Class uncertain; Archaeospira ornata Yu, A. imbricata Yu and Cambrospira sinensis Yu of Class Gastropoda; Heraultipegma yunnanense He et Yang of Class Rostroconcbia: hyolithids and some other uncertain skeletal fossils. Although the systematic position of this peculiar fossil is unknown at present, it is inferred that this genus may be one of the typical primitive animal groups based on the characters of the shell and the spe cial spines. The shell is bilaterally symmetrical, elliptical in apical view; the dorsal side is roundly convex with three different forms of dorsal spines and several pairs of marginal spines on the anterior margin. Judged from the general morphological characters of the bilaterally symmetrical shell, these lower animals, generally speaking, have adapted themselves readily to different circumstances, and reduced resistance to any directional movement necessary for varied physiological activities. As to the function of the shell’s characteristics, the narrowly rounded side may serve as the anterior. Such a model of the body helps these animals go on with their benthonic creeping or swimming life. On the other hand, the dorsal spines are different from each other in shape, size, mode of arrangement and in number; especially, the end of the hook-shaped spines is generally curved outward, while the geniculate spines are oblique outward, and curved posteriorly all of a sudden. These structures of mechanism also provide us with the evidence that the narrowly rounded side serves as the anterior, while the opposite end as the posterior.It is of particular interest that this genus is somewhat similar to Phylum Mollusca, especially to the tryblidiids of Class Monoplacophora, in some morphological characters, such as: 1) the bilateral symmetry of the shell, 2) the outline elliptical in apical view and cap shaped in lateral view and 3) the dorsal side generally roundly convex. After careful study, it has been found that since this genus is strikingly different from monoplacopharans, may be it belongs to another interesting group of skeletal fossils. The reasons for this are: 1) in the former, there are many pairs of marginal spines on the anterior margin, while in monoplacophorans, no marginal spines can be seen; and 2) in this genus, the sculptures are different from each other in different areas, not only in shape and number, but also in the mode of arrangement, whereas in monoplacophorans, they are identical with each other in the same type and shape. Judged from the different forms of dorsal sculptures, this genus is comparatively similar to such uncertain shelly fossils as Lepidites Zhong, 1977 emend. Yu, 1987 and Xiadongoconus Yu, 1979 from the same horizon in the Yangtze Region of China, but differs from the latter two genera in the presence of marginal spines on the anterior margin. In addition, this new genus also differs from brachiopods and other skeletal fossils in the peculiar type of the shell. According to the above comparison, this genus is entirely different from all the classes of Phylum Mollusca, possibly representing another interesting group of skeletal fossils. It is impossible to determine the exact taxonomic position of this genus until more materials are available.