THE CUMIDJE 301 



Definition of the siib-order Gumacea. 



The carapace covers the segments of the head and all 

 but the last five segments of the trunk. The antero-lateral 

 lobes are drawn towards one another usually in advance of 

 the frontal region. The first maxillipeds carry a respira- 

 tory organ of which the hinder division almost always is 

 furnished with branchial sacs, and the front division forms 

 an exserted tube during respiration for the outflow of 

 water from the branchise. Of the pereeopods at fewest the 

 first pair have exopods. Of the pleon-segments the fifth 

 is the longest. The appendages of the sixth are the only 

 pair of uropods. 



The eight families included are the Cumidae, Vaun- 

 thompsoniidge, Leuconidas, Nannastacidas, Campylaspidas, 

 Pseudocumidao, Lampropidas, Diastylidas. 



The peculiarity of the fifth pleon-segment being the 

 longest is reproduced in the curious Isopod genus Phrea- 

 toicus, Chilton, which is otherwise nearer the Amphipoda. 



Family 1. Cumidce. 



The first antennas are very small, with one of the 

 flagella rudimentary ; the second antennas in the male 

 have the filiform flagellum composed of many short joints. 

 The mandibles have the anterior branch produced and 

 armed with a dense lateral series of spines. The epipod 

 of the first maxillipeds is very large, with the branchial 

 sacs numerous, leaf-like, in a straight series. The third 

 maxillipeds have some of the joints expanded and laminar. 

 Only the first pair of perseopods in either sex have well- 

 developed exopods. The male has five pairs of pleopods 

 well developed. The inner branch of the uropods is one- 

 or two-jointed ; the telson is wanting. Five genera are 

 included in this family. 



Cuma, Milne-Edwards, 1828, has the carapace mode- 

 rately developed, only four segments of the trunk 

 distinct behind it ; the eye well developed ; the 

 third maxillipeds with the second joint apically 



