318 S. I. Smith — hJiirlj/ SUiffcH of Ilippa tdlpoiihi. 



The iilxlouu'i) is smaller aiul has much less freedom of motion in the 

 mesial phmc than in most Brac^hynran zoea^ The first segment is 

 not clearly (litt'erentiated from the thorax. The second, third, fourth, 

 and fiftli segments are entirely without ap))endages; the second and 

 third are nearly equal in length and sub-cyrnuli-ical ; the fourth is 

 slightly shoi'ter and is exj)anded considerably at the posterior ex- 

 tremity ; and the fifth is about as long as the fourth, compressed 

 vertically, and broadly exj)anded at the posterolateral angles so that 

 it is about twice as broad as long. The sixth segment is consolidated 

 with the tclsoii, forming a broad, lamelliform, caudal a])pendage about 

 as long as tlu' middle breadth of the caraj)ax. The a])pcndages of the 

 sixth segment (Plate XLVIII, fig. 10) ai-e small, rudimentary, 

 Oppressed to the under side of the telson so as to be hidden from 

 above, and are eac^h (composed of a stout basal segment and a single 

 narrow lamella (the outer) tipped with two slender setse, of which the 

 outer is about as long as the lamella itself and the inner much longer. 



The lateral nuirgins of the telson are slightly curved outward aiul 

 unarmed, but project )»osteriorly into a stout tooth each side of the 

 strongly arcuate ]»osterior margin. This postei ior margin has, in all 

 tile zoea-stages here described, a remarkably complex armament of 

 ciliated spines and miuute teeth (Plate XLVIII, tigs. 1:5, 14, 15). In 

 a considerable iiumbei- of specimens in tlu' third and the last stages, 

 the mnnber of these ciliated sj)ines is usually twenty-six, of whicli 

 the eighth, counting (Voni either side, is the largest, and the sixth 

 and tenth usually the next in size. One of the specinu'us in the 

 second stage (Plate XLVIII, iig. 1:5) conforms stiiiily with this: 

 there arc two sub-nu'dian spines (r/, </, Iig. i;5) separated by a single 

 denticle, then each side a slightly larger sj»ine (A, h) separated from 

 the sub-nu'dian ones by a single denticle, then four alternately 

 smaller and l:irg(>r spines [c, d, ('.,/') se|»arated from each other by 

 two denticles at each intors])ace, the outer (/') of these four sjtines 

 beino" the eighth, c(»unting from either side, ami the largest. Outside 

 this large sjtine there arc, each side, seven smaller sj)iiu's separated by 

 interspaces which increase toward the outer margin and are armed 

 with from two to nine denticles. The space between the outer spine 

 each side and the tooth of tlu' lateral margin is gri'ivtei- than any of 

 the interspaces bctwi-en the spines and is armed with twelve or thir- 

 teen denticles. In the other specimen in this stage there are only 

 twenty-five spines, a single niediiin spine (Plate XIA'III, tig. 14,^^) 

 taking the place of the two sub-nu'dian spines and the denticle 

 between them ; otherwise the Sj)ini'S and denticles are essentially as in 



