Family Cypridinidae. 



Fam. Cypridinidae. G. S. Brady aiul A. M. Norman, 1896, p. 638. 



Sub-Fani. C ifpridininoi' + f!>nh-¥iim. FhUomedinae (purt.). H. W. Mi'MJOl!. 1!M»() 1). p. 12. 



,, ,, ,, ,, ,, ,, ,, ,, J.M_. pp. r>, z4. 



Description: — Shell: — With or without .sexual diuiorphism. — The rostral incisur 

 is in most forms rather deep, iti others, on the contrary, more or less shallow, but is never, 

 however, quite absent; the upper lip of the incisur does not grow over the under one. The selvage 

 varies in type, but is always lamelliforni and most frequently well developed both on the 

 rostrum and along the greater part of the ventral margin of the .shell; it runs about parallel 

 to and somewhat within the free edge of the valve. The list runs from the rostral incisur in 

 an even, unbroken bow along the ventral and posterior edge of the shell, and finishes at the 

 back near the hinge of the shell (exception among the hitherto known forms: Siphonostra and 

 Cypridinodes. cf. below, the diagnoses of these sub-genera); it is sometimes narrow throughout 

 its whole length or else somewhat broader at the back; the distance from the list to the edge 

 of the shell is, on the average, somewhat greater along the back edge of the shell than along 

 the ventral edge. The valves, as in all forms belonging to the s t r a c o d s, are joined 

 along less than half the periphery; in only a single one of aU the genera so far known, the genus 

 Gigantocypris (cf. below, the diagnosis of this genus) are they joined along more than half the 

 periphery of the valves. The males never have a ring of hairs round the posterior part of the shell. 



First antenna: — This has more or less strongly marked sexual dimorphism. 

 — The sensory bristle of the fifth joint developed very variously, sometimes entirely absent 

 in the females. The original sixth joint has always only one bristle, placed distaUy-medially. 

 Distally this limb has seven to eight bristles, three to four of which are probably to be 

 considered as belonging to the original seventh joint and four to the original eighth joint. The 

 anterior bristle on the original seventh joint (a-bristle, cf. below, the terminology for the sub- 

 family Cypridininae) is never developed in the shape of a claw. 



Second antenna: — In a number of forms this limb is characterized by sexual 

 dimorphism, in others it is almost or entirely without it. — E n d o p o d i t e: In the female 

 most frequently rather small and weak, sometimes even more or less entirely reduced. In the 

 male this branch is sometimes of the same type as in the female, sometimes it is developed as 



