Le genre Tornquistes(Ammonitina,Pachyceratidae) á l'Oxfordien inférieur et moyen en Europe occidentale

TornquistesLemoine, considered still now as a subgenusof Pachyceras is up graduated to a genus level in the family PachyceratidaeBuckman. The study of this genus, only known in the upper part of Lower Oxfordian and the lower part of the Middle Oxfordian, shows six species; one of them, T. multicostatum, is new. These species are put in two sub-genus, Tornquistes s. str. and a new subgenus, Pachytornquistes. Some species are polymorph and for the first time, macroconch-microconch dimorphism is proved. Phyletic connections, stratigraphic repartition, paleobiogeographic distribution and their consequences are pointed out in conclusion.     

Modalités d'installation et d'évolutiondes Harpocératinés (ammonitina A) au Domérien inférieur dans le sud-Ouest de l'Europe (France,Portugal)

In Mesogea, the Harpoceratinae were known asearly as the end of the Lower Carixian. They later reached the sub-boreal province through the Alps or the South of the Iberic Peninsula. The analysis of the populations met in four crosssections of the Lower Domerian (Causses, Mâconnais, Franche-Comté, Portugal) showed the settling down of the Protogrammoceras isseli group that set up and evoluated in a similar way in the different areas in spite of a certain originality.On the one hand, it gave the cladogenetic groupP. monestieri-nitescens by diminution of the ribing density, strengthening of the ribs and simplification of the suture.On the other hand, a slower evolution give, near the end of the Stokesi zone, P. normanianum in the Paris Basin and in Burgundy, and P. lusitanicum in Portugal. At the same time, a new invader, P. celebratum, arrived in the Causses (and in Portugal).     

Relation métabolique entre l'arginine et l'acide γ-aminobutyrique dans le fruit de Castanea sativa: étude préliminaire de l'arginase

Analysis of the free amino acid pool in the chestnut fruit (Castanea sativa) shows that it is high in γ-aminobutyric acid. A metabolic connection between arginine and γ-aminobutyric acid is evident. Three enzymatic activities are involved: L-arginine ureohydrolase, L-ornithine 2-oxo-acid aminotransferase and L-glutamate carboxylyase.     

Le rôle du système nerveux central sur les mécanismes de l'oviposition chez Carausius morosus et Clitumnus extradentatus

Cephalic nervous connexions were found necessary for oviposition and normal egg maturation in the two species studied. Neurosecretory cells of A type from the brain, suboesophageal, thoracic, and four abdominal ganglia seem to elaborate a stimulating substance for egg laying. This neurosecretion type is not present in corpora cardiaca, corpora allata, the four last abdominal ganglia, or perisympathetic organs which have no clear-cut effect on oviposition. The circadian rhythm of egg laying appears to be entirely controlled by the liberation of this neurosecretion and by an inhibitory factor localized in the head.In Carausius, egg deposition by the valvulae of the ovipositor is regulated by these two factors whereas egg transit through the common oviduct is a distinct preliminary step under nervous control. This nervous effect from the posterior region does not exist in Clitumnus.     

L'âge du complexe récifal des côtes de meuse entre verdun et commercy et la stratigraphie de l'oxfordien dans l'est du bassin de Paris

The question of the age of «Hauts de Meuse coral rag is studied again using new faunas of brachiopods and ammonites collected above, below and inside the coral rag. Ammonites fauna of the well known «Calcaires de Creuë is revised. Results obtained agree closely.The «Hauts de Meuse coral rag grew up during Middle Oxfordian time; and extend part of the Plicatilis zone (Antecedens Subzone) and the whole Transversarium Zone up to the basis of the Bifurcatus Zone, for the first time identified in Lorraine. So it span a short depositional time, about 1 MY, with a high deposition rate, the thickness of the coral rag being more than 100 meters, reaching 150 meters in Saint-Mihiel area. Towards SE, on the other side of the Marne Gap, the sudden change into basinal facies go with a reducing of thickness and deposition rate.Upper Oxfordian deposits show a relative uniformity of facies and thickness. At the top of Middle Oxfordian limestones, the age of the discontinuity and the Sequanian renewal of deposition is basal Bifurcatus Zone. Erosional renewal and terrigeneous deposits are a wide spread event by the beginning of Upper Oxfordian.In the paleontological part, species upon which are based new ages and interpretations are only figured, except the species new or with new paleontological data, which are described. Type specimen of Perisphinctes mosensisBayle, from the «Calcaires de Creuë, is described and photographically figured for the first time.     

Ultrastructures nouvelles et non identifiées dans les calcaires de l'oxfordien supérieur de la champagne berrichonne

A scanning microscope study of the upper Oxfordian foliated limestones of the western part of the Berry region of France has revealed new, but unidentified, well-conserved organisms, which are described and illustrated in this publication.     

Cycles embryonnaires et sécrétion de la cuticule chez l'embryon de blatte, Blabera craniifer

Cuticle deposition has been studied with the electron microscope in cockroach embryos (Blabera craniifer) during normal incubation in situ and in culture in vitro, in the absence or presence of inokosterone (a phytoecdysone).Two cuticles are deposited successively during embryonic life, respectively between stages 11 and 17, and stage 21 and 24 hr after hatching. The occurrence of two embryonic cycles is thus demonstrated, the first ending at stage 17 without exuviation since there is no old cuticle to be shed, the second one at hatching.In embryos explanted at stage 17 and cultured in vitro, the formation of cuticle 2 occurred at the same rate as in situ. The addition of inokosterone (50 μg/ml) to the medium resulted in the early onset of cuticle deposition (in 3 days as compared with 15 days in situ) in legs previously cut at the base of the tarsus. Cuticle 2 was completed within 9 days after explantation (as compared with about 20 days elapsing in the normal embryo between stage 17 and the completion of cuticle 2). Unsectioned appendages were insensitive to the hormone.Regeneration of sectioned legs, which occurred normally n vitro in non-treated embryos, was completely inhibited in the presence of inokosterone, presumably because the hormone caused early immobilization of cells through accelerated cuticle formation.Results suggest that embryonic cycles are controlled by the same hormonal mechanism as larval cycles.     

Ostéologie et position systématiquedu genre Thrissops Agassiz, 1833 (sensu stricto) (Jurassique supérieur de l'Europe occidentale) au sein des Téléostéens primitifs

The osteological study of the genus ThrissopsAgassiz, 1833 (sensu stricto) from the Upper Jurassic of Germany and France allows to define the systematic position of that fossil fish within the primitive Teleosts. The general shape of the skull, the jaws, the ethmoidal area, the circumorbital bones, the fronto-parieto-supra occipital area, the parasphenoid and the opercular bones are all characters which prove that Thrissops belongs to the family Ichthyodectidae (order Ichthyodectiformes, super-order Osteoglossomorpha). However Thrissops is more primitive than the other Ichthyodectidae which are all of Cretaceous age. It possesses indeed two parietals bearing pit-lines, a premaxillary and a maxillary normally developed, a palatine and a metapterygoid without any contact, a denticulated entopterygoid, three free epurals and six uroneurals, while, in the Cretaceous Ichthyodectidae, the parietals are fused in one bone without any pit-line, the premaxillary and the maxillary are hypertrophic, the palatine touchs the metapterygoid, the entopterygoid is toothless, the epural disappear or fuse with the terminal neural arches to form supplementary neural spines, and the uroneural are only five.     

Biogéographied'un groupe d'Échinides cénozoiques (Echinolampas et ses sous-genres Conolampas et Hypsoclypus)

Echinolampas is a subtropical genus living in rather shallow water; one may regards it as a climatic marker. The theory of continental drift affords a rather good explanation for its distribution in space during Cenozoic era. It appears in Old Wolrd during Paleocene and it occurs in Central America during Middle Eocene; that implies it had to cross the already broad Atlantic Ocean; but at that time this ocean is not as broad at it is now. Migration along the shelf area which rimmed North Atlantic might have been impossible, owing to disruption of land connection between Europe and North America. Probably the migration occured in low latitudes and pelagic larvae were transported by one of the two equatorial currents. Diversity of the genus has much decreased during Late Eocene. The cause may be chiefly due to climatic deterioration, resulting from marine communication between North Atlantic and Arctic Ocean. Echinolampas occurs for the first time in Australia during Oligocene. One may suggest the possibility of a link between this late evidence and the quite remote position till then of Australian continent. During Miocene, the relative decrease in Echinolampas diversity in the Mediterranean Basin occurs as a result of the welding between Asia and Africa.     

13C NMR des alcaloïdes des Strychnos: Les dérivés de l'harmane et de l'usambarensine

¹³C NMR spectra of some tertiary and quaternary indole alkaloids are recorded and the signals assigned. Graphic interpretation of off-resonance spectra and substituent shielding effects together with the effect of N_b-methylation are utilized in the spectral interpretation.     

Nouveaux brachiopodes Chonetacea du Dévonien de la Cordillère cantabrique (Nord-Ouest d e l'Espagne)

The study of Chonetacean Brachiopods from Cantabrian Mountains allows to recognize several new taxa restricted to this area. A new genus and seven species of which six are new, are described in this paper; their vertical distribution is from Gedinnian to Upper Givetian: Chonetes bediae n. sp., Chonetes? kerforneiRenaud, 1942, Plebejochonetes coliensis n. sp., Plebejochonetes moniellensis n. sp., Luanquella cantabriensis n. g., n. sp., Plicanoplia sotoi n. sp. et Longispina truyolsi. n. sp. The species kerfornei, from the Middle Devonian of Armorican Massif is cited here for the first time from Spain.     

Le genre RichterellaAvram (Ammonitina,Périsphinctidés) dans le Tithonique inférieur de la bordure ardéchoise (Sud-Est de la France): Dimorphisme et variabilité

Dimorphism in the genus RichterellaAvram is confirmedon the basis of material collected in Ardeche (South east France) principally in the beds of the Fallauxi zone, from the localities of Le Pouzin and Broyon. The microconch, R. richteri (Oppel), lacks lateral lappets but a ventral horn, formed by the strongly projected forward secondary ribs, is present. The macroconch is «Lemencia praerichteriDonze & Enay. These two forms are united in the same species, R. richteri, and then in the same genus, Richterella. The microconch, which is generally better preserved than macroconch in the studied material, shows a greater variability of ribbing than previously thought, due to the poor illustrations of the lectotype of richteri (reproduced here) which showed only dichotomous ribs. The genus Richterella loses its original dimorphic sense and since its origins and its possible derivations are unknown, it became a taxon defined on morphological bases. The forms from Ardeche bear a greater resemblance to the Spanish ones than they do to the Roumanian forms. The stratigraphical and faunal contexts of Richterella in Ardeche are discussed in this work.     

Structure d'adhérencedes grains de pollen en tétrade du genre Classopollis PFLUG, 1953, de l'Hettangien de Saint-Fromont,Manche (France)

Palynological inventory of Saint-Fromont pit 0815 (Manche, France) related to Hettangian seems to show the conspecificity of Classopollis chateaunoviReyre, 1970, Classopollis kieseriReyre, 1970 and Classopollis harisiiMuir & Van Konijnenburg-Van Cittert, 1970. SEM pictures exibit some sculptural elements interpreted as structural attachments of grains in tetrad and compared to those of genus DicheiropollisTrevisan, 1971.     

Stabilité de l'espèce et évolution: La théorie de l'équilibre intermittent («Punctuated equilibrium)

Paleontologists' traditional conceptions on evolution do not seem to be in perfect accord with these of biologists. The gradual phyletism is compatible neither with E. Mayr's model of the Founder, nor with the actual stability of most of the paleontological species. The punctuated equilibrium model proposed by N. Eldredge & S.J. Gould offers a solution which integrates both paleontological observations and the data of modern biology.     

Le genre Leguminocythereis (Ostracodes) dans le Paléogène nord-aquitain: Espèces et populations; histoire évolutive locale

The genus Leguminocythereis, well represented inWestern Europe, is followed in North-Aquitaine (France) throughout the Eocene and at the basal Oligocene.Four species are described: L. striatopunctata, L.inflata, L. pertusa, L. aff. scrobiculata. The first two ones are polymorphic.The genus has suffered severely by the gradual setting of Eocene/Oligocene climatic crisis. Effectives grow less, specific populations structures are simplified; L. pertusa and L. aff. scrobiculata only are known at the basal Oligocene.By their locally irreversible distribution in time, themorphs appear as good stratigraphic indicators. Some of them are closely linked to special palaeoenvironments and are their markers.A comparison between the variances of some characterssuggests that, when they are isolated (out of the polymorphic structure) or/and in less favourable living conditions, the morphs develop an adaptative strategy by increasing of their genetic variability.Observed data are relevant of microevolution.     

Découverte de Stringocephaluseet autres Stringocephalidae (Brachiopodes Terebratulida)) dans le Givétien d'Afghanistan

A lot of Stringocephalidae have been discovered,for the first time, in the Givetian of Afghanistan. Among these we have identified: Stringocephalus aff. burtini (Defrance)), St. (Parastringocephalus) dewalense n. sp., Rensselandia aff. circularis (Holzapfel)). The locality is situated in Hazarajat, in a Devonian sequence which is more than one thousand meters thick and the age of which ranges from Gedinnian (probable) to Frasnian.