Chilton. — On some Subterranean Crustacea. 89 



I have now to add another obtained from the same well as the other 

 Subterranean Crustacea that I have described. 



Genus Phreatoicus, (novum). 

 Body long, sub-cylindrical, laterally compressed. Upper antenna 

 short, lower long, with flagellum. Mandible with an appendage. First 

 pair of legs subchelate, others simple ; first four pairs articulated to 

 body at the anterior ends of their segments and directed forwards, 

 last three articulated at posterior ends of their segments and directed 

 backwards. Abdomen long, of six distinct segments, last joined to 

 telson. Sixth pair of pleopoda biramous, styliform. Telson large, sub- 

 conical. 

 Phreatoicus tyiricus, sp. nov. PI. IV. 



Eyes not visible. Upper antenna about half as long as the peduncle of 

 the lower antenna, consisting of about eight joints, peduncle not distinguish- 

 able from the flagellum, last three or four joints thicker than the preceding. 

 Lower antenna about three-fourths as long as the body, peduncle of five 

 joints, first two short, third longer but not so long as the fourth, fifth 

 nearly as long as the third and fourth together. First pair of legs subchelate, 

 propodos rather small, palm oblique, defined by densely haired knob ; 

 finger strong, hairy ; next three pairs of legs subequal, rather stout ; last 

 three longer, setose, increasing regularly in length from before backwards. 

 First segment of pereion only about half as long as the second, remainder 

 subequal. Pleon two-thirds as long as pereion, first segment small, next 

 three subequal, fifth large, about as long as the preceding three together, 

 the second, third, fourth and fifth segments having the integument pro- 

 duced inferiorly, and the inferior edge fringed with short stout sette. Sixth 

 segment joined to telson and bearing a pair of biramous pleopoda ; peduncle 

 longer than rami, outer ramus shorter than inner. Telson large, sub- 

 conical, deeply concave below, inferior edge irregularly serrate and fringed 

 with very short setaa ; regularly rounded above, extremity projecting back- 

 wards, with short setaa on tip, and a stout one on each side of the 

 base. 



Colour — transparent. 



Length, about half an inch. 



Hab. Pump at Eyreton. 



Additional remarks on structure : — 



The upper antenna (pi. IV., fig. 2) is peculiar in having the last three 

 or four joints considerably thickened, the thickening being chiefly due to 

 the increased thickness of the integument. Small simple auditory cilia are 

 foimd on the under side of the antenna (fig. 2 a). 



Tbe lower antenna (fig. 3) has already been sufficiently described. 



