1916.] S. Kemp : Noks on Crustacea Decapoda. 381 



race that he recognises, the difference between the European and 

 Japanese races consisting solely in the greater variability exhibited 

 by the latter. 



The Indian specimens do not show any marked variation, but 

 the series is small. And even should their form prove constant, 

 it is useless to speculate on the precise status of the different races 

 until some general consensus of opinion on the Japanese forms has 

 been reached. 



Crangon crangon appears to be very rare on the Indian coasts ; 

 the only specimens in the Museum are the following ; — 



-'--^^" Akyab, Arakan coast. F. SloHczka. 5. ,3-52 "ini. 



The Structure of the Pleopods in Pontophilus. 



The recognition of the fact that in certain species of Pontophilus 

 there are often marked differences between the sexes in the form 

 of the pleopods, and that the species themselves also differ to a 

 great extent in the development of these appendages, has led me 

 to re-examine the material available in the Museum collection. In 

 the Indian Museum twenty-one species of the genus are represented, 

 a very considerable proportion of those that are known ; but , un- 

 fortunateh^, in the case of thirteen only do we possess examples of 

 both sexes. 



x-llthough iti the development of the pleopods there is a certain 

 amount of intergradation, it is possible roughly to classify the 

 species according to the development of these appendages into 

 five groups : — 



Group I. 



P. norvegicus, M. Sars ( ^ ^ndopod of last four pairs of 

 P oyacilis Smith ' pleopods well developed m both 



P. trevhostrls. Smith ) '^f '' '""'^^ conspicuous appendix 



' interna. 

 P. spinosus, lycach, P. abyssi, Smith, and P. occidentalis, 

 Faxon, represented in the collection by female specimens onl}^ 

 doubtless also belong to this group. 



Group II. 



Endopod of last four pairs of 

 pleopods comparatively well deve- 

 loped in male, reduced in female. 

 P. sculpi'us (Bell) ] Appendix interna present in male 



on all four pairs, but somewhat 

 rudimentary on the last ; in female 

 present on 2nd and 3rd pairs, rudi- 

 mentary on 4th and absent from 

 5th. 



P. incisus, sp. nov 



P. australis, Thomson 



P. chiltoni, Kemp, known from female specimens only, also in 

 all probability belongs to this group. 



