200 DUBLIN UNIVERSITY 



concealing lateral lobes and peduncle of external antenna?. Lateral lobes 

 small, arising internal to external antennae. Internal antennae three- 

 jointed. External antennae (?). Cephalothorax : coxae well developed. ' 

 Abdomen : coxae of first and second somite obsolete ; coxae of third to 

 fifth well marked. Telson : coxae obsolete ; posterior pleopods unco- 

 vered ; peduncle triangular, truncate at apex ; accessory lobe minute, 

 arising from superior border of peduncle. Accessory appendage subu- 

 late. Ischium arising from inner margin near apex of peduncle, short and 

 conical. 



Species. — Pyrgoniscus cinctutus. 



Body broadly oval, smooth. Head deeply embedded in coxae of 

 first cephalothoracic ring ; frontal lobe cleft in the median line, broad, 

 flattened, and squared, completely concealing lateral lobes ; lateral lobes 

 small, quadrilateral. Cephalothorax : coxae of first somite irregularly 

 quadrilateral, expanded in front, and touching produced frontal lobes ; 

 coxae of second to seventh somites quadrilateral, a raised transverse me- 

 dian ridge marking each somite. Abdomen : coxae, third to fifth somite 

 curved backwards. Telson deeply excavate at sides ; apex broadly, 

 truncately rounded. Posterior pleopods : peduncle broad, filling space 

 between telson and fifth somite, inner border excavate at base, outer 

 border straight, apex rounded, the whole representing a right-angled 

 triangle, with truncate apex. Accessory appendage about one-third 

 length of peduncle, which conceals it. Ischium arising from inner 

 margin of peduncle a little below its apex, subulate, minute, scarcely 

 attaining apex of peduncle, which is squared. 



A narrow raised ridge marks insertion of legs beneath cephalotho- 

 racic somite, this is produced backwards, as a tooth, passing beyond 

 posterior margin of somite. 



Locality : Eastern Seas. 



In many of its characters this genus approaches the Armadillidae, 

 near which family it should doubtless stand. The characters of the 

 lobes of the head are but an exaggeration of the form of arrangement 

 prevailing in some of that group. Unfortunately, in the specimen shown 

 me the external antennae were injured. Mr. White informs me it 

 was procured in the Eastern Seas during the exploration of H. M. S. 

 Herald. 



