REPORT ON THE CUMACEA. 



DEFINITION OF THE FAMILIES. 



All the known families, except one, the Pseudocumidge, being represented in the 

 Challenger collection, I have found it advisable to give here short diagnoses of the 

 same, and to enumerate the several genera contained in each of them. It may be 

 remarked that these families do not seem to have strictly the same systematic value as 

 those of the Schizopoda characterised in my former Eeport. The latter should perhaps 

 more properly be regarded as groups of a higher rank, or as sections. 



1. CUMID.E. 



Integuments generally strong, calcareous. Tail not sharply defined from the trunk ; 

 in female very slender, cylindrical ; in male much stronger, and with distinct epimeral 

 plates. Eye generally present. Antennulse very small, with one of the flagella 

 rudimentary. Antennae in male with posterior part of peduncle distinctly biarticulate, 

 flagellum filiform and composed of numerous short articulations. Mandibles well 

 developed, with the anterior branch produced and armed with a dense lateral series of 

 spines. E^^ipodite of maxillipeds very large, navicular ; gill-lobules numerous, leaf-like, 

 arranged in a straight series ; terminal plate of exopodite scale-like and strongly indurated. 

 Second pair of gnathopoda rather large, with some of the joints expanded and laminar. 

 The four posterior pairs of legs in both sexes simple, without any trace of exopodites. 

 Five pairs of well-developed pleopoda present in male. Uropoda with both branches 

 biarticulate, or the inner uniarticulate. Telson quite wanting. 



Genera. 



1. Cuma, Milne-Edwards. 



2. Cyclaspis, G. 0. Sars. 



3. Steplianomma, G. 0. Sars. 



4. Ij}hinoe, Sp. Bate. 



5. Cumopsis, G. O. Sars. 



2. VaUNTHOMPSONIIDjE. 



Integuments thin, squamous. General form of body, antennulae and mandibles much 

 as in the Cumidje. Eye present or wanting. Antennas in male with flagellum composed 

 of very elongate and slender articulations. Epipodite of maxillipeds (in female) very 

 narrow, with only few and digitiform gill-lobules arranged in a semicircle ; terminal 

 plate of exopodite membranous. Second pair of gnathopoda with the joints scarcely 

 expanded. The three anterior pairs of legs in female, and all but the last in male 



