NATURAL SCIENCES OF PHILADELPHIA. 167 



Descriptions of a New Species of CALLIANIDEA Ed. 

 BY THEO. GILL. 



CALLIANIDEA LiEVICAUDA Gill. 



The rostrum is equilaterally triangular, obtuse, and the carapace curved out- 

 wards from its base; the carapace over the external antenna? projects abruptly, 

 and is separated from the margin above by a short fissure ; the antero-lateral 

 margins of the carapace are abruptly extended outwards, and thence curved 

 obliquely downwards and posteriorly. 



The large cheliped is smooth and polished, and is about twice as long as the 

 carapace. The ischium is compressed and dilated anteriorly, with the articula- 

 ting surface for the meros oblique and scarcely emarginate ; the meros is nearly 

 a third longer than the ischium, subovate, flat internally, convex externally 

 above with its inferior margin anteriorly tridenticulate and hairy ; the carpus 

 is vertical, twice as high as long, and with its posterior side internally inter- 

 secting the anterior; its posterior articulating process is about as long as 

 broad, and is divided into two unequal parts by a wide groove on its inner side ; 

 it projects acutely below, and is there tridenticulate ; the manus is oblong, three 

 times longer than the carpus, with parallel borders : its intero-superior border 

 is provided with a long row of hairs, and its superior surface has a few distant 

 fascicles of hair; the inferior margin is crenulated, and there is on each side a 

 row of fascicles of hair ; the digital process of the manus is about two -thirds as 

 long as the manus itself, and it has five tubercles at its posterior half, the anterior 

 of which is largest ; anterior to this it is crenulated, as are also the margins on 

 each side ; the dactylus is moderately curved anteriorly, and crosses the digital 

 process of the manus, leaving a hiatus; above, it is rounded, with a row of 

 hairs on each side, the interior of which is very dense; below, the external 

 margin of the cochleariform excavation is anteriorly crenulated, succeeded by a 

 moderate tubercle, and posteriorly with two large ones, the posterior of which 

 is rather an elevated apophysis ; the internal border is anteriorly crenulated ; a 

 few pits with fascicles of hair are between the ridges of the cochleariform exca- 

 vation and on each side. 



The first pair of maxillipeds are smooth and polished on their external sur- 

 faces, and their internal margins are ciliated with long hairs. On the internal 

 surface of the ischium there is a longitudinal, distinctly pectiniform ridge ; the 

 meros, carpus and manus have each a longitudinal row of hairs on their inner 

 surface. The ischium is very slightly curved, and its margins are nearly paral- 

 lel. The meros is shorter, with an oblique tooth internally on its anterior third, 

 and thence more slender. The carpus is slender at its base, and internally very 

 convex at its anterior half. The manus is narrowed from near the base to its 

 termination. The dactylus is widest at the middle, and anteriorly rounded. 



The exognath of the outer maxilliped extends beyond the middle of the 

 meros. 



The outer antennae are about half as long as the internal, and the penulti- 

 mate joint is the longest. 



The median lamina of the caudal fin is rounded at the end, and its margin is 

 not ciliated. The lateral lamina increase progressively but little in length, 

 and each one bears a ridge which is continued almost to the margin. 



The feet of the second pair are provided with long hairs on their internal 

 borders. The feet of the fourth pair are nearly as much compressed as the an- 

 terior, and the basilar article is much enlarged. 



This species agrees very closely with the description of the Callianidea typa 

 of Milne Edwards, (Hist. Nat. des Crustaces, vol. ii. p. 320) but on a compari- 

 son with the figures it appears to differ in the form of some of the joints of the 

 IS 59.] 



