摘要:

SUMMARY1A quantitative investigation of the marine bottom fauna has been earned out, in conjunction with an analysis of the physical environment, across the continental shelf off Accra from the shore to a depth of fifty fathoms.2The concept of “community” used in the present work is discussed and defined.3Although the nature of the bottom sediment is of primary importance, wave action in shallow water and temperature in deeper water are important factors in community differentiation.4Four distinct infaunal communities have been recognised associated with four different types of bottom conditions, these are:(a) The Inshore Fine Sand Community (0 to eight fathoms), dominated by the polychaetesOwenia fusiformisandDiopaira nea/polilanawith the lamellibranchCultellus tenuis.(b) The Sandy Silt Community (8–20 fathoms), withTurritdla annvMaandSternaspis scutata.(c) The Silty Sand Community (20–25 fathoms), dominated by two species of Foraminifera–JullienellajoetidaandSchizamminasp.(d) The Coarse Sand Community (25–50 fathoms), dominated by the coralCaryophyllia clavus.5At depths greater than fifty fathoms a rock epifauna exists which is Mediterranean in nature and contains many new faunal records for West Africa. It is characterised by massive colonies of the coralDendrophyllia rameaand large numbers of the basket starAstrospartus mediterraneus.The bottom temperature at this depth varies little from similar depths in Northwest Africa and the Mediterranean.6The communities off Accra are clear cut and well defined and this is considered to be largely due to the rapidly changing nature of the bottom deposits across the shelf. These rapid changes in bottom conditions are caused first of all, in shallow water, by the sorting action of the surf waves on the bottom deposits. In deeper water a second transition is brought about by the production of coarse sediment from the erosion of a limestone deposit on t

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1958.tb00562.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SUMMARY1The testes are permanently abdominal in position and there is no scrotum. The testes are globular. The caput and cauda epididymidis are similar in shape and size. The vasa deferentia open into the collecting tubules of the seminal vesicles.2The seminal vesicles are large glandular bodies, divisible into an anterior glandular portion and a posterior ductus portion. The paired ducts open into the muscular urethra on the summit of a crista urethrae.3The prostate is a compact glandular mass, lying outside the muscular urethra below the neck of the bladder. It completely surrounds the muscular urethra only in the breeding season; at other times it is incomplete along the dorsal side. Its ducts are numerous, and open into the muscular urethra independently near the crista urethrae.4The muscular urethra is a simple muscular tube between the bladder and the penis. The genital ducts open into it.5The urethral gland which surrounds the muscular urethra is minute and is covered by the muscle of the urethra. The numerous short ducts of the urethral gland open into the muscular urethra.6A utriculus prostaticus is absent.7Cowper's glands are large and lie in the region of the muscular urethra into which they open by a pair of short ducts.8The penis is large, pendulous conical and directed caudally. It is divisible into three regions.The glans is large and complicated in structure. Its surface is covered by numerous minute denticles. There is a deep gutter projecting into the substance from its distal dorsal side. There are three lips, one ventral and two dorso‐lateral, at the tip.The corpora cavernosa together are horse‐shoe shaped in section and enclosed in a common sheath; but internally the two are separated by the septum. The corpus spongiosum is simple and surrounds the penile urethra up to the external orifice. An accessory corpus cavenosum is absent.The os‐penis is a simple cartilaginous curved plate, pointed terminally. It is restricted to the distal half of the glans.The penile urethra presents a pair of blind diverticula at its distal end.9The whole genital system shows a marked enlargement in size during breeding s

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1958.tb00563.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SUMMARYA total of 309 skulls of wild guereza moakeys from one small area in Liberia is described in detail for the chief purpose of contributing new data on the exact degrees of variability in non‐human primates for ultimate comparisons with the variability in past and recent populations of man. Three different forms ofGolobusare represented in this material, namelypolykomos polykomos(Zimmermann),badius badius(Kerr) andbadius verus(Van Beneden). It seems quite likely that the latter two are different species, rather than subspecies.Polykomosis the largest andverusthe smallest of the three. Sex differences in size are generally most marked inpolykomosand least inbadius, the former also being more variable than the other two. On a general average the measurements of the facepart of the skull are much more variable than those of the brainpart. Preliminary comparisons regarding the variability of cranial dimensions show little difference betweenColobusand most other primates for which corresponding information has become available.Among the distinguishing characters of theseColobtisthe degree of prognathism is to be specially mentioned, since it is very marked inpolykomosin contrast toveruswhich is orthognath.Veruaalso differs from the other two forms by having the proportionately largest orbits and narrowest inter‐orbital region. The orbital roof is much thinner inpolykomosthan in the smaller species. The relative position of the cranio‐vertebral joint differs somewhat according to species and to sex, it being most orally situated inverus, most aborally inpolykomosand regularly more orally in females than in males.The temporal lines do not approach each other as closely, nor meet nearly as often inpolykomosas in the other two species. Sagittal crests develop by far most frequently in maleverusin which they often extend forward over a large part of the frontal bone. These crests increase with advancing age particularly in specimens with comparatively small braincases. Occipital crests are best developed inpolykomosand least inverus, which lacks this structure in numerous specimens.As the absolute dimensions, so are the relative ones, or indices, more variable for the splanchnocranium than the neurocranium. The degrees of variability of cranial indices are roughly alike inColobusand in other wild primates from limited regions. The number of infraorbital foramina varies intensively in all theseColobusseries, but the number of mental foramina is fairly stable. The formation of the pterion region varies in allColobusin a high degree, often even on the two sides of the same skulls. A parieto‐sphenoid contact exists in three‐fourthsof the polykomos, but in less than half of thebadius.Rare and abnormal cranial variations are not nearly as frequent inColobusas in the man‐like apes. Some of these variations are evidently of a hereditary nature. Bregmatic bones, e.g., are fairly common inbadiuswhereas totally absent inpolykomos.The ascending arms of the intermaxillary bones are highly variable in allColobusand inbadiusthey frequently reach the frontal bone and can occasionally even meet above the nasal bones. In the lower lateral corners of the intermaxillaries there are symmetrical accessory sutures in eightColobus.These sutures run diagonally to the rim of the alveoli for the lateral incisors and have never been found so far in any other primates except in gorillas, which possess them with remarkable regularity.Suture closure is recorded in detail. Most facial sutures remain open much longer than those of the braincase, but even the latter persist inColobusto relatively much later stages of life than in the man‐like apes. The exact sequence of suture closure can vary considerably, but no more than in most other simian primates. The interfrontal suture, which normally closes early in postnatal life, was found open in several adultColobus.Such cases of metopism, extremely rare in other monkeys and apes, are apparently not uncommon amongColobusaccording to the literature and these new instances.Among the few juvenilesColobusin the present material there are several indicating that the permanent molars tend to erupt relatively earlier in this genus than in the great majority of monkeys and apes. InColobus, as in the other genera of the Colobinae, underbite is much more common than in the remaining catarrhines and overbite is extremely rare.The present series of skulls and dentitions of wild‐shotColobuscontains in general comparatively few cases with malformed or diseased conditions. These are described with particular reference to their frequency. Healed fractures have been found in three skulls and ten others show signs of infections, mostly in the orbital region. By far the most frequent pathological conditions are represented by alveolar abscesses which exist in a fairly high percentage of the oldest specimens. Not a single case of caries could be found and only one instance of a supernumerary tooth, but congenitally lacking teeth exist

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1958.tb00564.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SUMMARYWild rats(Battus norvegicusBerkenhout andR. rattusL.) were kept in large cages fitted with nest boxes and supplied with excess food and water. Colonies varied in size from four to twenty rats, and were usually maintained for at least nine weeks. The rats were individually identified and their behaviour studied in detail.Rattus norvegicus.In all‐male colonies there was a low mortality and most of the rats increased in weight. In colonies containing both males and females, mortality was high among the males, very low among the females; most of the males declined in weight, though some grew well. There was however no fighting for females. It is suggested that the extra fighting which took place in these colonies resembled displacement behaviour and was due to excitement evoked by the presence of females combined with frequent frustration.There were no deaths in all‐female colonies, or in colonies of litter mates. Unless parturient, normal females did not display aggressive behaviour except in ‘play’.Males, but not females, added to established colonies, were attacked by resident males and usually died, sometimes within a few hours and often without visible injury.At the beginning of an experiment there was much exploration, both of the cage and of the other rats. Social relationships were established early. Male members of the colonies fell into three classes: (i) alphas, which were the equals or superiors of other males in the colony, and attacked newcomers; (ii) betas, which adapted themselves to a subordinate role, and were ingratiating towards newcomers; (iii) omegas, which were persecuted by one or more alphas and soon died. Alphas and betas gained in weight; omegas lost weight. There were more omegas in male‐female colonies than in those consisting only of males. Amicable behaviour (apart from coitus and care of young) was shown by both sexes and was based mainly on contact ‘releasing’ stimuli: the most specific of a number of amicable responses was crawling under the belly of another rat. Fighting involved a series of stereotyped acts, including tooth chattering and a characteristic threat posture; there was much wild leaping, but biting produced only superficial damage.Rattus rattus.A small number of experiments withR. rattusshowed that this species possesses all the components of amicable and aggressive behaviour observed inR. norvegicus, but that it is less fierce and more agile. There was no evidence of extra conflict in male‐female colonies. All‐male colonies containing both species were usually peaceful.R. rattusof either sex added tonorvegicuscolonies were usually attacked, but not with such intensity or consistency as were malenorvegicus; if attacked, they died.R. norvegicusmales added torattuscolonies were sometimes attacked, but they did not die.Displacement behaviour and abnormaľ sexual and aggressive behaviour were observed in both species.General.There is no reason to think that dominance hierarchies ever develop in wild rat colonies. Members of a single family do not attack each other. The fighting of wild rats is essentially territorial, not for any specific object. Aggression is most readily evoked in males established in a familiar area, faced with a strange adult male of the same species. In normal females aggression occurs only in defence of a nest containing young. Social responses consist of stereotyped behaviour patterns which are probably innate; but learning plays an important part in determining the choice of response and in secondary adjustments of behaviour to partic

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1958.tb00565.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY