DESCRIPTION OF GENERA AND SPECIES. 



Order CUMACEA. 



Family I. Cumid^e. 



The most characteristic feature of this family is the total want, in both sexes, of 

 exopodites on the four posterior pairs of legs, a character not found in any other known 

 group of Cumacea. These legs also exhibit a very simple structure, and possess only a 

 scanty supply of bristles. On the other hand, the males are distinguished by the 

 presence of five pairs of well-developed pleopoda, and there is only one other family, 

 Vaunthompsoniidse, which agrees with the Cumidse in this respect, whereas the males of 

 all other known Cumacea either have a less number of these limbs, or want pleopoda 

 altogether, as in the females. As a character peculiar to this family may also be 

 mentioned the highly indurated and strong integuments, the full development of the 

 branchial apparatus, and the total want of a telson. 



Of the five genera comprised within this family, only the genus Cyclaspis is repre- 

 sented in the Challenger collection. 



Cyclaspis, G. 0. Sars, 1864. 



Cyclaspis, G. O. Sars, Om den aberrante Krebsdyrgruppe Cumacea og dens nordiske Arter, p. 81. 



Generic Characters. — Carapace large and swollen, almost globular, with the dorsal 

 line strongly curved, and the pseudorostral projection very slight ; a distinct notch on 

 each side anteriorly beneath the latter projection. Ocular lobe more or less produced, 

 and usually having at its end a distinct eye. Only four segments of the trunk exposed 

 behind the carapace, the anterior rather large, the three others suddenly much narrower, 

 and scarcely broader than the caudal segments. Tail very slender and elongate, last 

 segment obtusely produced at the tip. Antennulse with one of the flagella very small, 

 knob-shaped, the other biarticulate, and bearing two long sensory appendages at the 

 extremity. Posterior Up with the lateral lobes armed at the tip with strong teeth. 



