134 G. 0. SARS. CRUSTACEA. [norw. pol. exp. 



and carries one ciliated seta behind, and 2 in front. The last joint is very 

 small and carries, on the tip, 2 slender claws of somewhat unequal size, and 

 in front of them a simple bristle. 



The succeeding pair of limbs (fig. 4) are considerably longer than the 

 preceding pair, and have the basal joint quite simple, without any spiniferous 

 projection at the end, but provided there with only 2 plumose setae. The 

 terminal part is almost 3 times as long as the basal one, and is divided into 

 4 well-defined joints ; it otherwise resembles m structure that of the preceding 

 pair, and is hkewise generally extended obhquely behind. 



The last pair of limbs (fig. 5) are very small and simple in structure, 

 extending, as a rule, obliquely upwards across the sides of the abdominal 

 portion of the body. They each form a slightly tapered stem, exhibiting 

 an imperfectly defined, small terminal joint, which carries 2 very slender 

 setae, one of which is more than twice as long as the stem. The function 

 of these limbs cannot be locomotory, since they do not admit of being extended 

 from the shell, whereas they most probably serve the same purpose as the 

 peculiarly modified last pair of limbs in the Cypridinidce, viz., that of cleansing 

 the body from foreign matter introduced into the shell-cavity. 



The caudal lamellae (comp. fig. 10) are not very large, and are of semi- 

 circular form, being movably articulated to the end of the abdominal division. 

 They are not exactly juxtaposed, the one advancing somewhat beyond the 

 other; and each is armed with 8 slender claws, rapidly increasing in length 

 distally, the foremost claw being considerably elongated, and placed at some 

 distance fi-om the others. The claws are finely denticulated along their 

 concave edge, and are movably articulated to the plate, which projects 

 between them in small dentiform processes. At some distance behind the 

 claws, 2 very small juxtaposed bristles occur. 



The adult male (PI. XXXV, fig. 3) is easily recognizable from the 

 female, both as regards the shell and the enclosed animal. 



The shell measures 3-20 mm. in length, and is accordingly somewhat 

 smaller than that of the female. Seen laterally (fig. 3), it also appears rather 

 narrower, with the posterior extremity more obliquely truncated, and the 

 upper posterior corner somewhat more prominent. The ventral margin, 

 moreover, is more distinctly sinuated in the middle. 



