342 DE. W. T. OALMAN ON NEW OR EAEE 



Family Diastylid^e. 



Gynodiaslylis carinata, gen. et sp. n. New Zealand. 

 ,, l(Bvis, sp. n. ,, 



„ costaia, sp. n. Gulf of Siam. 



„ bicristata, sp. n. j, and Japan. 



Paradiastylis longipes Calm. „ 



Colm-ostylis pseudocuma, gen. et sp. n. New Zealand. 

 Diastylopsis elongata, sp. n. „ 



,, crassior, sp. n. „ 



Diastylis koreana, sp. n. Korea. 



„ fistularis, sp. n. Gulf of Siam. 



„ insularum Calm. New Zealand. 



It is not pretended that this list, with that published in the first part of the paper, 

 accounts for every specimen in the collections submitted to me. A certain number 

 remain over which may represent undescribed species, but they are solitary, immature, 

 or mutilated specimens, undistinguished by any striking features, and descriptions of 

 them, necessarily incomplete, would only add to the perplexities of future students of 

 the group. In addition, there are a considerable number of male specimens of the 

 genera Cmnella and Nannastacus which, as explained below, have so far defied my 

 eiforts to reduce them to systematic order. 



In working through this very extensive collection, together with other collections 

 from tropical and southern seas reported on elsewhere, the infrequency with which 

 known species have been recognized has been very striking. We seem to be dealing 

 only with random samples from a very rich and varied fauna, and there can be 

 little doubt that the vast majority of existing species of Cumacea still remain to be 

 discovered. "While the group is far more abundantly represented in tropical seas 

 than had been supposed, much more extensive collecting will be necessary before it is 

 possible to compare the number of species with those found in boreal and arctic waters ; 

 certainly the warmer seas have nowhere been found, as yet, to yield the enormous 

 numbers of individuals occurring, for instance, in favourable localities on the Norwegian 

 coast ; and, as in many other groups of animals, the tropical species are far inferior in 

 size to those from the colder regions of the north. 



The manifest imperfections of our knowledge make it useless to attempt at present 

 any general discussion of the geographical distribution of the Cumacea. Provisional!}^, 

 however, it may be said that the collections hitherto examined show a remarkable 

 preponderance, in the warmer seas, of the Bodotriidae (especially the genus Cyclasjjis) 

 and Nannastacidse (especially Cumella and Nannastacus) and a paucity of Diastylidae 

 and Leuconidae. Further south, in New Zealand, as in the Magellan and other sub- 

 antarctic regions, and in the Antarctic Ocean, the Diastylidae and Leuconidte reassert 

 themselves. 



