摘要:

The spawn of five Stylommatophora, one basommatophoran, one prosobranch and one opisthobranch were each desiccated at 25 °C and at various constant relative humidities, and in almost still air. The experimental apparatus incorporated glass “fishpole” balances and a time‐lapse cine‐camera. Differences in desiccation rates were found to be due to differences in size of the experimental objects, the larger egg‐masses losing water at a relatively slower rate than the smaller.At equilibrium with the atmosphere the marine spawn retained more water than those from other habitats. Different water‐retaining capacities probably reflect interesting biophysical characteristics of the mucus of diffe

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb03058.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

The large animals of Nairobi National Park have been censused intermittently once a month from mid‐1960 until the end of 1966. Of the 23 species discussed, the density per kilometre has been determined accurately for the following: Grant's gazelle, Thomson's gazelle, water‐buck, impala, wildebeest, hartebeest, eland, buffalo, warthog, giraffe, zebra and ostrich. From these figures the biomass has been calculated for each species each year. After a peak biomass of 12,775 kg/sq. km during the drought of 1960–61 the population declined to and remained fairly level at about 5690 kg/sq. km from 1962 to 1966. This figure includes about 1050 kg/sq. km of cattle and sheep. The large predators account for only about 1.4%of the total biomass of wild animals while removing about 15.5% from this group ann

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb03059.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

This study records estimations of the chronology of certain events in the calendar of development of the quokka. One gestation period of between 25 and 26 days was observed and 22 joeys (young) had an average birth weight of 0.3852±0.0436 g. Vacation of the pouch occurred between 185 and 195 days of age. One thousand joeys were found to have a masculinity of 0–453 which is statistically smaller than parity. An estimation was made of the age at which the separate teeth erupt and a method of approximating the ages of juveniles and yearlings proposed by using dental eruption stages. The youngest recorded ages at which males and females became reproductively mature were 389 and 252 days respectively. After attaining reproductive maturity all animals born in captivity bred throughout the year. Animals taken from Bald Island, although showing seasonal breeding in the wild, will breed without periodic anoestrus interruption when taken into captivity. Captive animals may live seven years or longer. Using the chronology of some of the above events a comparison was made of the reproductive potential of the wild and domesticated populatio

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb03060.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

A radiological study of the developing dentition of the domestic albino ferret has revealed the presence of four upper and three lower deciduous functionless incisor teeth in each half of the jaw. The presence of the additional upper incisor tooth can only be accounted for in two ways:(1) It arose as the result of a gene mutation within the closed colony.(2) It is indicative of the fact that at some early date in the evolution of the Carnivora, four deciduous incisors were functional in each half of the jaw.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb03061.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

A descriptive and interpretative account is given of the hyo‐laryngeal apparatusof Solenodon cubanus, known previously only from Peters' (1863) incomplete description of the type specimen. The constitution of theSolenodonhyoid arch is discussed, with particular reference to the fate of its tympano‐hyal elem

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb03062.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

The development of the mother‐infant relationship is expressed in terms of the change in typical relative positions of the pair and in the pattern of contacting and leaving they showed.Rainy periods increased the time the infant spent asleep with its mother, the effect being more than that produced by the infant's age on sleeping time in the first three months of life.Rate of development of mother‐infant relationships was compared with that of Rhesus monkeys in similar conditions, and found to be very closely comparable.Interactions by infants with other baboons were found to be quantitatively and qualitatively different for each available demographic class (though some classes were only represented by a single individual). Results illustrated different rates of social maturing in the sexes, differential behaviour of the adult male towards the sexes of infants, and the existence of a special relationship between siblings.Interactions of neoparturient mothers with other adults are characterized by high overall frequency, with a high frequency of avoiding of friendly approaches by the mother. Both these have returned to normal frequency levels in the third month.Restriction of infants by mothers was seen only in the caged group. Its immediate effects on the behaviour of the infant and its association with other maternal social behaviour are descri

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb03063.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Information on the food habits of stoats and weasels was obtained chiefly from gut analyses of carcasses sent from various parts of Britain. Lagomorphs, small rodents and birds form the bulk of the food taken by these predators. The three food classes appear to be equally important to stoats, whereas weasels obtain nearly half of their food from small rodents.Microtuswas the most important small rodent in the diet of both stoats and weasels. Game birds were taken more by stoats than weasels; the chief bird prey of the latter was passerines.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb03064.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Trotting and galloping strides of various pecoran species are analysed from motion picture sequences. Why a species uses one of these gaits when not closely pursued in preference to the other is discussed with reference to basic differences in the gaits, to the environment in which the animal lives and to the animal's size and possession of large horns or antlers.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb03065.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Descriptions of eight blastocysts, two embryos and 41 foetuses are given. Methods of estimating the age of these are discussed, and a modification of Huggett&Widdas's (1951) formulae used. The phenomenon of “delayed implantation” is discussed and a more realistic nomenclature is proposed. Both the method of comparison for blastocysts and embryos and the statistical treatment of the foetuses indicate that the recommencement of development occurs over a period of two months with a mean date at the end of the second week in February for the Orkney and Shetland group. There is a suspense of development for about 100 days. The specific foetal growth rate is shown to be similar to that of other mammals (apart from Cetacea and Primates). The significance of the 100 days suspense in interpreting the abnormal spring pupping in the Pembrokeshire group of Grey seals is discus

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1968.tb03066.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY