THE CRUSTACEA 



shows, at most, only indistinct traces of segmentation (Cytherella). 

 The terminal part is curved ventrally, and ends in a caudal furca. 

 In the Myodocopa the furcal rami are flattened triangular plates, 

 with short, stout spines or teeth on the hinder margins (Fig. 37, E). 

 In the Podocopa they are slender or styliform, bearing setae, or 

 may be much reduced, as in the Cytheridae. 



FIG. 34. 



A, antennuleof Cypridinametliterranea, 9. B, antenna of Conchoecin marina, 9. C, antenna 

 of Cytherella soniuta. D, antenna of Daririnvla stevensoni. (After G. W. Miiller.) en, endopo- 

 dite, ex, exopodite, according to Miiller's interpretation. 



Appendages. The antennules may function as sensory organs, 

 or they may be used for swimming, creeping, or digging in sand, 

 and their form and armature of setae or spines are correspondingly 

 varied. Each is composed of eight segments in Cypridina (Fig. 

 34, A) and in Pontocypis, and this seems to be the typical number 

 from which the others have been derived by reduction. In the 

 Halocypridae the segments are reduced to two or one. Sometimes 



