593.5 251 



IV 



A Carcinological Campaign 



DURING the last few months there has been remarkable activity 

 in discussing and describing new and peculiar forms of the 

 smaller Crustacea. 



At Liverpool last autumn Mr A. O. Walker (15) announced his 

 new Cumacean genus Leuconopsis, in which the male has on the 

 second joint of the third foot a pair of curved blade-like processes, 

 the feature unique, the function not yet explained. 



In the Transactions of the Royal Irish Academy, Mr W. T. 

 Caiman (3) has enriched the caridea or true shrimps with a new 

 family, Bresiliidae, established for a specimen taken at a depth 

 of 750 fathoms off' the south-west coast of Ireland. In the 

 Transactions of the Royal Society of Edinburgh, Mr Caiman (2) 

 has re-described and re-figured the Anaspidcs Tasmaniae of G. M. 

 Thomson, with a view of discussing the systematic position of this 

 extremely interesting crustacean. It is found in Tasmania in pools 

 at an elevation of 4000 feet. It is in structure at present quite 

 unique. This combination of uncommon form with uncommon 

 habitat led its learned discoverer to say that " owing to long isola- 

 tion it has undergone very profound modification." But it may 

 equally well be supposed that its isolation has enabled it to retain 

 characters which in other crustaceans have been profoundly modified. 

 Reasons are given by Mr Thomson for the opinion that the ancestral 

 forms of Anaspidcs found their way from the sea into the streams 

 and lakes of Tasmania as far back as Mesozoic times. Its thoracic 

 limbs being divided into walking and swimming branches, it has 

 reasonably been grouped with the Schizopoda or " cleft-foot " 

 shrimps, and in some respects it seems to come nearest the 

 Euphausid family, so distinguished for luminous organs. To such 

 organs I fancied that the minute group of ' ocelli ' on the back of 

 the head, which Mr Caiman has pointed out, might perhaps belong, 

 but .the guess has found no favour, although visual ocelli can 

 scarcely be needed to supplement the stalked eyes. In the seg- 

 ments of the trunk the animal is rather like an amphipod, which it 

 also resembles in having simple branchial vesicles. But these are 

 in pairs. Mr Caiman speaks of this latter circumstance as without 

 parallel in adult malacostraca, overlooking, it would seem, the 



