摘要:

SUMMARY.The prawnsAnchistioides antiguenais, Penaeopsis goodei, andPenaeopsis smithicome to the surface at regular intervals through the year about an hour after sunset. The intervals coincide with the time of the new moon, but the numbers reach a maximum on the second night of the lunar month and again on the twenty‐sixth night.Penaeopsishas a seasonal fluctuation, the numbers being greatest in the summer (June, July, and August), whileAnchistioidesis less frequent in July and August and again from December to March. The summer reduction is due to the dying out of a generation in July; the winter scarcity to seasonal conditions.Some data are given suggesting a growth periodicity inAnchistioides, the moults among captive adults occurring more frequently from the eighteenth to the twenty‐second day, and again on the twenty‐eighth day than at other times during the lunar month.The factors controlling periodicity are again reviewed, and the effect of light selected as the most likely one, inhibiting the activity of the prawns, but being occasionally subject to interference by non‐regular conditions such as the opacity of the water.Observations onPenaeus brasiliensis, Periclimenes americanus, andLeander affinisshow that these prawns are subject to similar control.Preliminary work on periodicity in the plankton by standard tow‐netting is

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1937.tb01684.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

摘要:

SUMMARY.This paper describes the external and internal anatomy of a new species of Ascothoracican,Baccalaureus torrensis.The more important points of difference between this species and those previously described are as follows:–(a)The segmentation of the thorax and the arrangement of the thoracic appendages shows a condition intermediate between that ofB. argalicornisandB. japonicus, and suggests the most probable way in which the four‐segmented thorax (found inB. japonicus, maldivensis, andhexapus)has developed from the six‐segmented condition (found in many other Ascothoracica).(b) The gut is loaded with large granules for the greater part of its length. The source and function of these granules is obscure, but similar granules occur in the Zoanthid tissue covering the mantle coils, in amoebocytes scattered in the body cavity, in the anterior part of the maxillary gland, and in large sac‐like structures at the anterior end of the thorax.(c) In addition to the maxillary glands there are other glandular structures within the thorax. The more dorsal of these may represent part of an antennal gland, whereas those placed ventrally may be similar in nature to the shell‐glands of an Ostracod.(d) There are certain differences in the detailed anatomy of the nervous system.(e) A pair of elongated tubules arise from the lateral parts of the oviducts and run backwards. It is suggested that these may be spermathecae.(f) The arrangement of the testis tubules also shows slight differences, as there are no collecting chambers at the upper ends of the vasa deferentia, immediately below the external openings of t

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1937.tb01685.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

摘要:

SUMMARY..1. The rediscovery of the Tasmanian CollembolaAnoura tasmaniaeandA. dendyidescribed by Lubbock in 1899 is recorded.2. These two species, together with the New ZeaJand speciesAnoura spinosadescribed at the same time, have been restudied, and are now shown to be properly placed in the genusCeratrimeriaBorner of the tribePseudachorutiniBörner.3. The three species are redescribed and figured.4. The relationships of all known species ofCeratrimeriaare discussed. It is shown that four geographical groups can be distinguished for the three great divisions of Gondwanaland, namely, America, Africa, and Indo‐AustraKa, and a fourth for Tasmania and southern New Zealand.5. It is suggested that the Indo‐Australian group may be the basic one from which the others have been der

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1937.tb01686.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY