350 ASELLID,E. 



maxillae are also very delicate, furnished with three 

 oblong-ovate terminal plates, setose at their extremities. 

 The legs are short and slender, all being formed nearly 

 alike, the four anterior ones being, however, rather more 

 robust and tuberculated on the basal joints, all terminat- 

 ing with a small slender curved finger. The tail consists 

 of six segments, of which the four basal ones are short 

 and equal, with the posterior margin entire ; the fifth has 

 the posterior margin irregular, and the sixth is large, 

 semicircular, flattened, with a slight central ridge; on each 

 side it bears a lateral appendage, of which the basal 

 portion is nearly square, with the outer margin notched, 

 and terminating in a strong, curved, movable spine ; the 

 apical portion forms a slender style, with strong bristles at 

 its extremity, which appears to be separated into a minute 

 articulation. The ovigerous pouch of the female consists 

 of four pairs of scales, affixed to the middle segments 

 of the body, and the tail is furnished on its underside 

 with six pairs of scale-like, branchial plates, forming three 

 rows, which are naked and of equal size. These plates 

 are received, as in the Sph<eromid(S, in a cavity formed by 

 the excavation of the underside of the caudal segments. 

 In this respect, and especially in the segmentation of the 

 pleon, the genus is removed from the remainder of the 

 Asellidae; indeed, Dr. Leach formed it into a distinct race 

 in his great family Cymothoada, which also included the 

 Serolidce, JEgida, and Sp/MBromida>. 



The whole of the dorsal surface is covered with stiff, 

 pinnated hairs, amongst which numerous minute para- 

 sites, somewhat like Echinorhynchi and Acari, are con- 

 stantly to be seen. They even infest the branchiae. 



