560 PROCEEDIXns OF THE NATIONAL MUSEUM. vol.xxiii. 



directed forward; between the depression and the posterior margin is 

 a compressed protuberance; between the protuberances the transverse 

 groove runs as a narrow cut I'ounded and enlarged at the bottom. 

 The antero-lateral angles of the second, third, and fourth segments are 

 produced forward in short, sharp spines. 



The epimera of the four anterior segments have projecting spines; 

 the lirst having a single spine, the other three having two spines each. 

 The three posterior segments of the thorax are very much the same as 

 in £J. fragilu; the spines on either side of the median line decrease in 

 size successivelv. 



The spine on the base of the abdomen is short; there are two con- 

 spicuous granules nearly in the center and bottom of the two longi- 

 tudinal depressions. The extremity of the abdomen is formed by a 

 decurved spine; the upper surface of the spine is concave; on either 

 side of the base of the terminal spine is a lateral triangular spine; 

 these lateral spines do not in any measure curve forward, as is the 

 case with E. fragilh. 



On the median line of the ventral surface of the thorax there is a 

 sharp, curved spine on the first segment, prominent longitudinal 

 ridges on the second, third, and fourth segments, and a spiny tubercle 

 followed by four longitudinal ridges. The ridges are separated by 

 transverse grooves on the coalesced fifth, sixth, and seventh segments. 



ITahitat. — Windward Islands, West Indies. 



Dej>tL—6S7 fathoms. 



Ti/jje.—Csit. No. 23911, U.S.N.M. 



58. ILYARACHNA G. O. Sars. 

 137. ILYARACHNA HIRTICEPS G. O. Sars. 



Ili/(ir<(cJm(t hirtlceps G. O. Sars, Forh. Vid. Sebk. i Christiania ]8W>, p. 167, 

 1870. — Hansen, Vid. Medd. naturh. Foreii i Kjoebh, 18S7, jx 195. 



JIahf'tat.—Q6° 32' N. lat., 55° 34' W. long.: TT^ lo' N. lat., 58° 56' 

 W. long.; 72° 41' N. lat., 59° 50' W. long. (Greenland). 

 Depth.— li)^ to 227 fathoms. 



V. ONISCOIDEA.. 



ANALYTICAL KEY To THE FAMILIES OF ONISCOIDEA. 



a. Inner anteniife with one to two articles. Pleopoda in five pairs; those of first 

 pair wanting; tliose of the second, third, fourth, and fifth segments have a 

 single l)ranch, all branchial; the branch of the first segment, however, in 

 the male, is produced on the inside in a long compressed stylet; pleojwda of 

 the sixth segment form an inferior operculum. 



Family XVIII. Tylioes (p. 561). 



a/ Inner antennte with three articles. l*leopoda in six pairs, all double branched. 

 External l>ranch of the first five pairs opercular in character. Internal 

 branch branchial, in the male, however, of the first and second pairs sexual. 



