860 THE VOYAGE OF H.M.S. CHALLENGER. 



are foliaceous and tipped with a thick fringe of hairs, a third that is sharply pointed and 

 single, and a fourth that is broad and foliaceous, extending forwards beyond the apex of 

 the previous one and posteriorly into the branchial chamber, and has the margin furnished 

 with radiating cilia. 



The first pair of gnathopoda is short and subpediform, consisting of six joints, of 

 which the terminal is small and tipped with five or six spine-like hairs, similar to others 

 that fringe the outer margin of the second joint ; it carries no branch attached to the 

 basisal joint, and only the rudiment of a mastigobranchial plate. 



The second pair of gnathopoda is long, slender, and pediform, and carries a long 

 basecphysis and a rudimentary mastigobranchial plate. 



The first pair of pereiopoda is slender and not very long, the chela is scarcely wider 

 than the carpos, and the fingers are long, slender, and parallel, the inner margins being 

 fringed with long and slender teeth, every third and fourth being longer than the others ; 

 the outer margin of the pollex is smooth, while that of the dactylos is armed with four 

 or five equidistant solitary spines. The second pair resembles the first and corresponds 

 in size. The three posterior pairs are shorter than the two first ; they are slender and 

 feeble, and carry a short basecphysis fringed with hairs that are jointed and ciliated ; 

 the ischium is armed on the posterior under surface with a strong tooth nearly as long 

 as the joint ; the meros is slightly lobed on the inner side, and is furnished with two 

 strong spines and five or six ciliated hairs ; the carpos is nearly as long as the meros and 

 lobed on the inner side anteriorly, the lobe being furnished with one small spine and 

 several long and ciliated hairs ; the propodos is shorter than the carpos, lobed on the 

 inner side anteriorly, but less so than the carpos, the lobe being fringed with four or 

 five ciliated hairs, but no spines ; the dactylos is longer than the propodos, the margins 

 are subparallel, increasing rather than decreasing in width until near the apex, where 

 they approach and terminate in a slightly uuguiculate point, the under margin being 

 fringed with a few hairs. 



The pleon is somewhat more slender than the carapace, and the sixth joint is abruptly 

 narrower than the preceding, and possesses the indication of a lobe on the anterior dorsal 

 extremity. 



The telson is long, slender, tapering, and armed with three strong spines on each side, 

 each spine being solitary and distant from the others. 



Leptochela gracilis, Stimpson (PL CXXXIX. fig. 2). 



Leptochela gracilis, Stimpson, Proc. Acad. Nat. Sci. Philad., p. Ill, 1860. 



Carapace cylindrical. Rostrum subequal with the ophthalmopod. 

 Pleon smooth ; fifth somite posteriorly produced to a horizontal tooth ; sixth somite 

 furnished with a tubercle near the anterior dorsal extremity. 



