摘要:

SUMMARY.1Part of a collection of gorgonopsids from Upper Permian rocks of the Ruhuhu Valley in Tanganyika is described. Detailed accounts are given of the quadrate‐articular hinge mechanism and the reflected lamina of the angular from fragmentary remains, and skulls ofScylacops capensisBroom andDixeya quadrataHaughton are described.2An attempt is made to restore the jaw musculature of gorgonopsids. It is concluded that the posterior pterygoideus muscle was inserted on the ventro‐medial surface of the articular and that a masseter was present and was inserted on the reflected lamina of the angular.3The evolution of the masseter muscle is discussed and it is concluded that it arose in captorhinomorph cotylosaurs, and that it was inserted on the deep Made of the angular in primitive pelycosaurs, and on the reflected lamina of the angular in all more advanced synapsids except the most advanced theriodonts.4The mechanics of retroarticular processes are examined. It is concluded that the deflected articular process present among synapsid reptiles generally was a true retroarticular process, giving attachment to a depressor mandibuli muscle, and that its ventral deflection was a modification to permit the wide gape necessary in forms having large canine teeth.5The nature of the typical synapsid middle ear is discussed. It is concluded that the available data are best accounted for by assuming that an external auditory meatus, a post‐quadrate tympanum and an extra‐stapes were present, and that the ear was sensitive to airborn

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1955.tb00589.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1955.tb00590.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

SUMMARY.1An African meliponid bee (Trigona (Hypotrigona) gribodoiMagretti) has been kept in observation nests near Accra, Gold Coast.2The nests had up to 750 bees, honey and pollen store cells of 8 mm. height and 6 mm. diameter and brood cells of 31/2 mm. height and 21/2 mm. diameter arranged in clusters.3The nests had a trumpet‐shaped tubular entrance and another tube running in to the nest. The nesting cavity is sealed where necessary by a thick propolis screen and the nest area may be cut off from the rest of the cavity by a wax sheet.4The queen is physogastric. Drones take thirty‐two days from egg laying to emergence, are reared in cells identical with those of the worker caste and perform no work. Workers take thirty‐five days to develop and after emergence pass through five recognizable stages of increasing pigmentation.5In the absence of a queen, workers lay eggs but only drones are reared.6The five stages of the worker caste perform work on a rotation system comparable with that of the honey bee. Stage 1 performs no work: stage 2 rears the brood and feeds all castes; stage 3 ripens nectar and cleans the nest: stage 4 ventilates the nest and carries debris out; stage 5 guards the entrance and forages for nectar, pollen and propolis.7A detailed description is given of activities in the nest.8Foraging takes place mainly in the morning.9There is a heavy brood mort

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1955.tb00591.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

SUMMARY.An investigation of the morphology, histology and functioning of the food canal and the associated haemal canals inEchinus esculentushas been carried out.Two kinds of secretory cell have been identified in the lips and pharyngeal wall which produce mucus and an acid secretion respectively. The oesophagus is lined with mucous cells. The stomach has an inner epithelium containing chains of fragile granules which are discharged from its free surface to provide extracellular enzymes. A layer of vacuolated cells which may assist absorption of liquids lies at the base of the epithelium. Amoebocytes of all kinds are present within the stomach wall and in the haemal channels. The siphon, intestine and rectum are lined by a cuticularized epithelium. The whole of the outside of the gut is covered with a ciliated peritoneum.Ingestion inEchinustakes place either by the action of the tube feet holding and presenting such food as sea‐weed to the mouth or by the teeth scraping food from the surface immediately below them. The co‐ordinated action of many muslces of Aristotle's lantern results in the opening or closing of the teeth.The pH of the gut graduates from 5·9 at the mouth to 6·3 at the stomach and 6·9 in the intestine.Water circulates through the mouth, pharynx, oesophagus, siphon and intestine, particularly during periods when the animal is not feeding, and probably serves a respiratory function.Experimental feeding ofEchinuswith iron saccharate shows that the substance is taken up by agranulocytes within the lumen of the stomach, transported through the stomach wall to the haemal spaces where association takes place with granulocytes so that clumps are formed. Migration of iron granules associated with amoebocytes takes place through the haemal canals to the radial and gonadial regions. There is no evidence to support Oomen's hypothesis that the granulocytes burst within the gut to provide digestive enzymes.The haemal system acts as a pathway for the migrations of the nutritive granulocytes as well as providing a system for the possible diffusion outwards from the gut of dissolved substances.The use of amoebocytes in the lumen and epithelium of the gut for carrying out some intracellular digestion and absorption is correlated with a poorly developed haemal system which lacks a pumping mechanism, with omnivorous feeding and a slow passage of food through t

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1955.tb00592.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

SUMMARY.The requirements for marking Seals are considered and a method is described for applying rings to the fifth digit of the pes in the Atlantic Seal, by using special pliers.The results of marking 176 Seals in 1968‐3‐4, on the Pembrokeshire coast, are given and show that, during the first, six months of the first year, moulterfi move as far north as Anglesey, west as far as the Wexford coast of Eire, and south to Cornwall and Brittany, as well as eastward up the Britsol Chan

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1955.tb00593.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

SUMMARY.1The development of the teeth ofSqualusandScyliorhynushas been examined in an attempt to clarify various aspects of their detailed structure and to provide a basis for comparison with other vertebrate teeth.2The enamel layer of the tooth is completely formed before calcification begins as a characteristic tissue, composed of a matrix penetrated by long cytoplasmic processes from the pulp cells and by reticular fibres passing inwards from the basement membrane. Calcification of the tooth commences in this enamel substance; during the process the matrix and reticulars alter in appearance and the cytoplasmic processes are replaced by fibres. The basement membrane calcifies where fused to the tooth, and the sharp‐edged ridges of the crown appear to be derived from this membrane.3The dentine appears as fibres laid down on the sides of the pulp, its appearance overlapping the beginning of enamel calcification; these intermingle with other fibres forming an irregular boundary fringe in the enamel and both extend upwards to enclose the apex of the pulp. The pulp cells whose processes penetrated the enamel substance become odontoblasts, and as the fibres enclose the pulp the truncated ends of their processes become enclosed in dentinal tubules.4The superficial similarity between the teeth of selacians and of higher types does not extend to the detailed structure of the teeth, and the question of homologies and relationships requires further work for its solutio

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1955.tb00594.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

SUMMARY.1An analysis has been made of some data relating to the longevity and fertility of the Orkney vole,M. orcadensis, as observed in the laboratory.2The probability of surviving the first three weeks of life, based on a total of 1,358 live‐born young, of which 1,250 were still alive at weaning, was 0·9205.3A total of 131 young of both sexes was observed between the ages of three and nine weeks, and of these 117 were alive at six weeks, and 114 at nine weeks of age. Combining the information for infant and juvenile mortality, some 20 per cent of live‐born young, taking both sexes together, died before reaching the age of nine weeks.4The adult expectation of further life at the age of nine weeks, based on the life‐histories of sixty male and sixty female voles, was for males, 90·3±2·95 weeks, and for females, 97·3 ±4·34 weeks. Taking both sexes together, the average expectation of life at birth was about 1·6 years.5. A total of 508 litters, consisting of 1,358 live young, waa recorded, giving a mean number of 2·67 young per litter. The largest number observed in any one litter was eight young. The mean number of young per litter, however, varied according to the age of the mother.6The observed span of reproductive life for females lay between the ages of nine and 123 weeks. A female, if she lived throughout this span, might be expected on the average to give birth to a total of 12·9 littens, consisting of 17·0 daughters, if an equal sex‐ratio at birth is assumed.7. The relation of fertility to the age of the mother was similar to that observed in other mammalian and some insect species, namely an initial risc to a peak, followed by a gradual fall as the age of the mother increased.8The intrinsic rate of increase of a population subject to the observed life table and age‐specific fertility rates, was estimated to be,r=0·072 per head of population per week. A population increasing at this rate would double in numbers in 9·6 weeks.9The longevity and intrinsic rate of increase of the Orkneg vole is compared with that of the mainland vole,M. agrestis. Judging from the available evidence, it appears that in the laboratory the Orkney vole is a longer lived animal, and its intrinsic rate of increase is less than that ofagreatis. This difference is due mainly to the fact that the Orkney vole has fewer young per litter, and because the females reach their peak of productivity at a more advanced age.10The expenses of this investigation were partly paid for hy a grant froin the Agricul

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1955.tb00595.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

SUMMARY.The primitive phonate family, the Ellobiidae, is discussed with reference to the structure, ecology and relationships of the following genera—Pythia, Ophicardelus, Cassidula, Ovatella, Leucophytia, Ellobium, Pedipes, Leuconopsis, Marinula, Rangitotoa, MelampusandCarychium. Ecologically, the family is shown to fall into four sections, a more primitive estuarine section, and sections containing marine intertidal, coastal terrestrial and inland terrestrial genera of rather more specialized character. In relation with detailed descriptions about to be published of the functional morphology of British ellobiids, a wider comparative account is now given of the digestive system and the genital ducts, and their evolution throughout the family. Further trends, chiefly concerning the adult and embryonic shell, are dealt with, in a discussion of the evolutionary pattern of the Ellobiidae. The frequent occurrence of parallel evolution, and the relative absence of adaptive radiation, or characters of obvious selective value, are noted. A scheme is proposed for the classification of ellobiid genera into subfamilies, which in some points departs from that of Thiele, based on radular studies by Odhner.A wider review is then given of the evolutionary significance of the Ellobiidae, with reference both to the evolution of pulmonates from prosobranchs, and to their relationships with primitive tectibranchs. Finally, the relationships of the Basommatophora and the Stylommatophora are discussed, and the significance of the Ellobiidae is pointed out, with reference to the origins of both groups. The Basommatophora are held to be a phylogenetically unnatural group. The Ellobiidae is the only family of this group that could have provided possible ancestors for Stylommatophora, and these are unlikely to have occurred among known genera. Reference is made to the geological evidence in support of the view of gastropod evolution presented from this stud

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1955.tb00596.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

SUMMARY.1A systematic account is given of a collection of ascidians from the shores of South Africa, containing thirty‐nine species.2One genus and ten species are described as new to science.3Only one species was found to occur on both the south‐west and east coa

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1955.tb00597.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

SUMMARY.An account is given of the morphology of the head region ofHemipipu carvalhoiexcluding the nasal cavities which were discussed in a previous publication (Paterson, 1951).The markedly fenestrated cartilaginous nasal capsule closely resembles that ofPipaand also shows similarities to that ofHymemhirus. InXenopus. however, the nasal region is better chondrified and approximates that of other Salientia.The nasals and frontoparietals are large, the latter being fused and provided with a conspicuous supraorbital ridge which also features inPipaandHymemchirus.There is no quadrato‐jugal, palatine or prevomer and the squamosal lacks the processus zygomaticus that occurs inXempus.The ventral surface is largely occupied by the broad parasphenoid, while the pterygoid, in common with that ofPipaandXenopus, is provided with an anterior process projecting forward towards the posterior end of the maxilla.There is a continuous cartilaginous subocular arch from the quadrate to the planum antorbitale.Only three foramina occur in the medial wall of the membranous labyrinth. These have been determined as the foramen endolymphaticum, the foramen perilymphaticum superius and a single foramen acusticum.The quadrate is massive and mainly cartilaginous. It is concluded that in the Pipidae a pseudobasal process developed from the larval palatoquadrate is connected to a basicranial ridge of the neurocranium by means of a post‐palatine commissure. The latter, which is regarded as belonging to the neurocranium, is probably comparable to the auditory ledge described in other Salientia.The sound‐conducting apparatus is essentially similar to that of other Pipidae, but lacks the small operculum that obtains inXempus.Although the complete hyoid apparatus was not investigated, it is evident that the adultHemipipaagrees withPipain the absence of cerato

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1955.tb00598.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY