摘要:

Chydorid cladocerans of three closely related genera–Chydorus, PeracanthaandPleuroxus– possess a long, blindly‐ending tubular organ which lies freely in the haemocoele but follows a precise course between the organs of the body, and which ultimately unites with the alimentary canal in the rectal region.No such organ is present inPseudochydorus globosuswhich, until recently, was assigned to the genusChydorus. This species, like representatives of at least seven, and probably more, chydorid genera, has a much shorter glandular organ which, although markedly different in form, may, however, be homologous with the tubular organ. InAlona affiniswhat is perhaps a precursor (or regressive rudiment) of a glandular organ is present. All these are described and the only partially‐elucidated situation inAlonella exiguais mentioned.InEurycercus lamellatusandLeydigia leydigiino trace of either a tubular or a glandular organ is present.The function of these organs is unknown. Mention is made of their possible phyletic and taxonomic signi

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1969.tb00702.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

This paper is based on collections made in Sabah by John Smart and on an examination of named material (types) in the British Museum (Natural History), London.Segregates discussed comprise:(1) six new species, (2) five named species from the area, described by the late F. W. Edwards (1933).

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1969.tb00703.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

African centipedes labelledScolopendra amazonica(Buecherl) andS. morsitansL. in the collection of the British Museum (Natural History) have been examined. All are regarded, at present, asS. amazonicabut in many respectsS. amazonicain Africa shows greater variation than doS. amazonicaandS. morsitansin India. North African populations are very distinct.

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1969.tb00704.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

Caraphractus cinctusis an arrhenotokous mymarid parasitizing the eggs of Dytiscidae under water. In the newly emerged female only fully formed eggs are present in the ovaries and the earlier stages of ovarian development have been studied in the pupa. The two ovaries each contain from 10 to 20 ovarioles depending upon the size of the female. The two lateral oviducts unite to form the vagina which is bent upon itself when laying is not in progress. The eggs are stored in the ovarioles and the female has remarkable control over the deposition of the eggs, since in most cases she rejects host eggs already parasitized, after probing them with her ovipositor. The spermatheca is a rigid capsule and the spermathecal duct at its base has a deep U‐shaped bend. There is a large spermathecal gland opening by its own duct into the spermathecal duct after the bend. The poison apparatus is well developed though the female does not kill the egg or paralyse the embryo host. The poison gland is of unusual shape being compact and rounded distally instead of tubular. Dufour's gland is large and buoyant. The ducts of both glands lead to the base of the ovipositor. The possible effect of their secretions in rendering a once parasitizedAgabusegg generally unacceptable for further laying is discusse

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1969.tb00705.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

The distribution ofArianta arbustorum, Cepaea nemoralisandC. hortensis, and the variations in the shell polymorphism of theCepaeaspecies have been studied in an area of low chalk downland and alluvial river valleys near Rickmansworth, Hertfordshire. The distribution ofA. arbustorumis restricted, the species being largely confined to the bottoms of river valleys, especially in hedgerows. Variations in dampness seem the most likely limiting factor.C. hortensisis widespread and found in many habitats, butC. nemoralisis largely confined to woods, and is especially common in beechwoods. The morph‐frequencies ofC. nemoralisandC. hortensisvary in such a way as to suggest the operation of climatic and visual selection. InC. hortensisthere are area effects for the presence or absence of pink five‐banded shells, and there is an overall linkage disequilibrium resulting in an excess of unbandeds in non‐yellow shells. Reasonable evidence for the operation of random factors in determining the morph‐frequencies of populations ofCepaeain the area has been found only for three very disturbed populations. It is suggested that the large number of selective forces known to act onCepaeapopulations in this area will account for the variation in morph‐frequencies in populations from the same area o

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1969.tb00706.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1969.tb00707.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

Eggs and larval development ofhates niloticusfrom Lake Chad are described. The pelagic eggs, averaging 0–83 mm in diameter, are characterized by a large single oil globule and a narrow perivitelline space. Hatching occurs at a remarkably premature ontogenetic stage, 1 ‐2 mm in length. Detailed descriptions are provided of subsequent larval development up to the earliest juvenile stages. The occurrence of buoyant eggs in freshwater and brackish‐water species, particularly lower percoids, is reviewed and comparisons are made with marine forms. A marked tendency for the relative size of the oil globule to increase with decreasing salinity is related to hydrostatic function. Demersal eggs in freshwater lower percoids are also discussed. Larval development inL. niloticusis shown to be similar to related forms but differences are noted in the stage at which hatching occurs and the position of the oil gl

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1969.tb00708.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

A new species ofHylais described, from the Pakaraima Mountains of Guyana. It superficially resembles members of theH. geographicagroup.

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1969.tb00709.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1969.tb00702a.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY