摘要:

Studies on the egg shells of a selection of Sphenisciformes, similar to previous ones on ratites and the Anatidae, have been carried out. The true shells, after removing the membrane and cover, were analysed for insoluble and soluble nitrogen, and studies were also made using histological and plastic embedding techniques.The combined studies indicate that, in addition to the large crystals running through the shell, there is often a thin layer of fine vertically orientated crystals above these. Then resting on this layer is a thin organic cuticle and usually, above this, a cover which is chiefly organic matter but contains some inorganic material. This cover is very marked in shells ofAptenodytessp. and is thicker at the poles than at the equatorial region. The histological picture of the true shell is very similar to that of the Anatidae.Most of the pore channels seem to be, at least partially, blocked with organic matter. Unlike the thickest Anatidae shells, there are few branched pores, although in the thicker shells the mouths of the channels have a shape like an arrow head.Plotting true shell thickness against parts per 10,000 of nitrogen in the true shell gives some separation of genera and to a lesser extent of species, but the results are not so clear cut as in the Anatidae.

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1965.tb01873.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Records of the jump ofGalago senegalensisare subjective and incomplete. Observation of the jump confirms the findings of previous authors but its suddenness and speed preclude any detailed account of the important period during which the animal maintains contact with the ground. Using high‐speed cinematography an analysis has been made of movement during this period. This photographic analysis provides sufficient data for estimates to be made of the tensions that the muscle groups concerned are required to develop and the distances over which they need to shorten.Summary(1) An account is given of observations made of the jump ofG. senegalensisin the field and in captivity.(2) A standing vertical jump of 7 feet 43/4 inches is recorded.(3) A photographic analysis of the earliest stages of the jump reveals (a) that the fore‐limbs take little part, (b) that effective use is made of the length of the synchronously acting hind limbs, and (c) that force is applied to the ground in the region of the tarsometatarsal joint.(4) A mechanical analysis provides estimates of the tensions expected to be developed by the quadriceps femoris and triceps surae muscle groups and shows that in the act of jumping the gastrocnemius requires to shorten only a small amount in order to produce a full excursion of the ankle jo

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1965.tb01874.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

The coelomocytes of the maldanid polychaetesClymenella torquata(Leidy) andEuclymene oerstedi(Claparède) (=Caesicirrus neglectusArwidsson, 1911) appear to be budded off from particular areas of the somatic peritoneum which overlie large blood capillaries in the thorax and trunk, and from more extensive areas of peritoneum at the posterior end of each tail segment. Both species have large numbers of phagocytic coelomocytes which are similar in structure and behaviour to those of some other polychaetes, and appear to have functions both of excretion and nutrition, and to play some part in regeneration. They have a tremendous capacity for ingestion which is shown particularly in late autumn, when they ingest and digest large numbers of disintegrating gametocytes, and after breeding, when they deal similarly with unshed gametes and debris.Clymenellahas a second type of coelomocyte which is not phagocytic. This type may contain haemoglobin, but the evidence is not conclusive

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1965.tb01875.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

This paper describes the structure of the pedicel ofHeteropoda venatoria(Linn.) (Sparassidae, Araneae), the banana spider, and illustrates the associated muscles. No attempt is made to assess the exact function and homology of each muscle, but consideration is given to their arrangement with respect to the free passage of blood between the prosoma and the abdomen, and to the observed movements of the abdomen in the living spider.

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1965.tb01876.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

The reduced right half of the pallial complex ofNerita tessellata, N. fulgurans, N. versicolor, N. pelorontaandNeritina virgineacomprises a hypobranchial gland, a vestigial gill and the opening of a duct which bears the same relationship to this gill as that of the left kidney to the functional gill. The duct leads from the region of the genital duct corresponding to the renal section of mesogastropods. The posterior part of the glandular genital duct lies in the visceral mass; its relationships are identical with those of the left kidney. The anterior part develops alongside the rectum within the anterior pallial vein. The left half of the pallial complex ofNeritaincludes a hypobranchial gland absent inNeritinaandTheodoxus.The floor of the mantle cavity ofNeritaforms an accessory respiratory surface, receiving blood from the anterior aorta. Its blood spaces communicate with the haemocoel and the parabranchial vein. This vein, also present inNeritinaandTheodoxus, drains the mantle skirt. InNeritaits importance increases when the snail is out of water and the mantle cavity is used as a lung.The buccal mass ofNerita fulguranshas the same basic organization as that ofMonodonta lineata:differences are related to specializations in the neritid radula requiring greater versatility of movement during feeding. It is protruded by lateral and ventral protractor and buccal depressor muscles originating on the body wall and inserted on the posterior radular cartilages. The horns of the anterior cartilages are orientated to the feeding ground by an array of levator muscles unparalleled in the trochid, and by the buccal fold which also spreads the radula and ensures its maximal sweep. The radular membrane is pulled outward by protractor muscles originating on the posterior cartilages and associated with a cartilage in the posterior wall of the sublingual pouch. Food is gathered on the back stroke of the radula which is drawn into the buccal cavity by a powerful retractor muscle associated with a radular diverticulum. The diverticulum is absent in trochids which have muscles for direct retraction of the buccal mass.The absence of salivary glands in neritaceans may be related to the development of the buccal fold; glandular buccal pouches and sublingual glands may compensate for their loss. The oesophageal glands extend through the anterior oesophagus to the buccal cavity; owing to their separation from the mid‐oesophagus they are unaffected by torsion. The stomach is a voluminous sac, simplified in that the caecum is lost or vestigial and that the major typhosole ends at the junction of the style sac with the proximal region. The gastric shield forms a tooth, very prominent inNeritina, which can protect the openings of the oesophagus and ducts of the digestive glan

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1965.tb01877.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

A list of the 18 species represented in the collection is given. Of these, two are here recorded for the second time, namely,Anchialina parvaIi andPleurerythrops inscitaIi. The female of the latter was hitherto unknown and is now figured. li's suggestion thatGastrosaccus philippinensisW. M. Tattersall might be synonymous with G.bengalensisHansen proved to be correct on re‐examination of types material of both. One species,Acanthomysis ornata, with very aberrant armature of telson and uropods, is new to science and is fully described and figure

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1965.tb01878.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

The life cycle and variation of the long‐tailed field mouse (Apodemus sylvaticmL.) on the Scilly Isles and Cornwall was studied by an analysis of samples collected at regular intervals from January 1961 to August 1962. Observations on population structure, reproduction and moult suggest that the life cycle of this species is similar on Scilly and Cornwall. Skull and body measurements revealed distinct differences between the samples from St Mary's, Tresco and Cornwall. Both the St Mary's and Tresco mice are larger than the Cornish form. St Mary's mice are larger than those from Tresco and have distinctly longer palatal foramina and pectoral stripes.SummaryFrom January 1961 to August 1962, 350 specimens ofApodemus sylvaticusL. were collected on St Mary's, Tresco and Cornwall.The life cycle was similar in each of the three localities studied. Juveniles were first present in the April and May samples, and survivors from the previous year were rare by August. Evidence from pregnant or lactating females and from juveniles suggested a breeding season commencing in February‐March and terminating by mid‐October. Testes of both first and second year animals were found to regress after August.Analysis of skull measurements revealed highly significant differences in mean lengths of the upper molar tooth row in the three samples, St Mary's mice being largest, Tresco mice intermediate, and Cornish mice smallest. This trend was also apparent from comparisons of occipito‐nasal length.St Mary's mice were found to have distinctly longer pectoral stripes and palatal foramina than Tresco animals. These two characters tended to be intermediate in mice from C

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1965.tb01879.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Seven of a sample of 11 specimens ofTilapiafrom Lake Kitangiri in the eastern Rift Valley of Tanzania are shown to belong toT. amphimelasHilgendorf andT. esculentaGraham. The other four are intermediate in structure and are interpreted as the result of hybridization. From this it is deduced that at least one of the species must have reached the lake recently, probably through the agency of man.A table of comparison of proportions and meristic characters in the two species and the intermediates is given, and in a postscript this is used as a basis for identifying specimens from Lakes Singida and Eyasi, the former of which is known to have been stocked.SummarySeven of a sample of eleven specimens ofTilapiafrom Lake Kitangiri in the eastern Rift Valley of Tanzania (Tanganyika) are shown to belong toT. amphimelasHilgendorf andT. esculentaGraham. The other four are intermediate in structure and are interpreted as the result of hybridization. From this it is deduced that at least one of the species must have reached the lake recently, probably through the agency of man.

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1965.tb01880.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY