16 



G. O. SAES. 



[No- 8. 



preceding; it terminates with a small incurved point and bears 

 at the extremity a short curved claw and a slender recurved 

 seta. 



The caudal rami (PI. Ill, fig. lOu, PI. IV, fig. 1), very mov- 

 ably articulated to the posterior extremity of the body and 

 generally, when not in action, closely applied against the ven- 

 tral face of the body, form two narrow chitinous plates lying 

 in close juxtaposition. They are almost linear in form, though 

 somewhat tapering from the base to the extremity, and bear 2 

 slender claws and 2 delicate setae. Of the claws the longer one 

 originates from the tip and slightly exceeds the half length of 

 the corresponding ramus; the other attached to the posterior, 

 of dorsal, edge at a short distance from the apex, is considerably 

 smaller, but of a similar form and as the apical one quite 

 smooth and but very slightly curved. Of the setae the smaller 

 one originates from the apex immediately in front of the termi- 

 nal claw, whereas the longer one is attached to the dorsal edge 

 at a short distance from the upper claw, the half length of 

 which it slightly exceeds. 



Between the caudal rami and the insertion of the 2nd pair 

 of le$s there is in the female on either side a broad rounded 

 lobe (PI. Ill, fig. 10c), projecting inferiorly — the genital lobes. 

 In the interior of these lobes a narrow, very tortuous canal 

 occurs, originating at the posterior, somewhat projecting corner, 

 and more anteriorly forming a rather large, almost globular 

 convolut; it is highly probable, that the spermatozoa are intro- 

 duced in the body through this canal during copulation. In * ne 

 male these lobes are converted into a pair of very complicated 

 copulative organs (see PI. IV, fig. 1), which admit of being 

 fully extended beyond the shell and during copulation become 

 introduced within the shell-cavity of the female and applied 

 against the genital lobes of the same. They are connected with 

 the body by a narrow neck (see figs 6, 7) and, when not in action, 

 are turned posteriorly in a horizontal direction, their extremities 

 projecting to either side of the insertion of the caudal rami 

 (see fig. 1). The organs are quite symetrical and consist each 



