Sub=Order I. Cypridiniformes. 



Gen. ,,(Jy p r i d i n es", H. MlLNE Edwakds, 1838, ]>. 178. ' 



., Cypridina, H. MlLXE ED\\AHDt>, 1840, p. 409. 

 Fam. Cypridinadae. W. Baihu, 1850 a, p. 176. 

 Sub-Fam. Cypridminae, J. D. Dana, 1852, p. 1281. 



Fam. Cypridinidae, G. S. Brady, 1868 b, p. 462. - 



G. W. MUller, 1894, p. 203. 

 ,, Asteropidae + Fam. Cypridimdae + Fam. Rutidermatidae + Fam. Sarsiellidae, 



G. S. Brady and A. M. Norman, 1896, pp. 628, 638, 673, 675. 

 ,, Cypridinidae, G. W. MOller, 1912. p. 7. 



Diagnosis: — Shell: — Has most often on the anterior border a more or h^ss well- 

 developed rostral sinus, placed at or a little beneath, rarely a bttle above, half the height of 

 the shell; its dorsal and ventral margins most often more or less convex; the hinge very seldom 

 with teeth; within the free edge of the shell a greater or less number of medial bristles*; 

 the edges of the valves without or with comparatively few glands; most often with a strong 

 incrustation of lime. . . 



First antenna: — Originates rather deep down on the front. Strong, more or less 

 elongated, with 5 — 8 joints; first joint quite without bristles, is directed more or less upwards, 

 and together with the next joint forms a decided knee, f)pen downwards. The original fifth 

 joint has, in the male always, in the females most often, distally at the back a powerful sensory 

 bristle, always (?) furnished with sensory filaments, termed ,,the sensory bristle of the fifth 

 joint", but apart from this this joint has no bristles at all. This limb is principally a sensory 

 and locomotory organ, as an organ of locomotion, however, it never co-operates in swimming. 



Second antenna: — The protopodite is situated on the side of the upper 

 lip. With a rather narrow base, very movably united to the body; large, relatively high, heart- 

 or pear-shaped flattened at the sides, with very powerful musculation, unjointed, without 

 any obvious traces of the boundary between the original joints; sometimes with a short bristle 



* Tliese medial bristles prevent foreign particles from entering the cavily of the shell but allow a free exit, 

 being, at least the outer ones, almost always directed outwards. 



