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



the dactylos ; the outer margin is armed with several small teeth, of which the largest is 

 at the anterior angle, the others irregularly lessening until they disappear near the 

 middle. The pollex is long, slender, gradually narrowing to the apex, where it is 

 pointed and curves to meet the dactylos : it stands at a slight angle with the propodos, 

 and gradually curves upwards. The dactylos corresponds in form and length conversely 

 with the pollex, against which it impinges when closed throughout the entire length by 

 a series of small leaf-like plates closely impacted sideways against each other, the points 

 being directed posteriorly. These fade away towards the extremities of the pollex and 

 dactylos, which overlap each other when closed. 



The second pair of pereiopoda is considerably smaller than the first, to which it 

 otherwise bears a general resemblance, excepting that the propodos is much more slender, 

 being not broader than the carpos, and has the margins fringed with long hairs. 



The third and fourth pairs are also chelate, but differ from the preceding in having 

 the curve of the dactylos in the opposite direction. The pollex is long and slender, and 

 armed with a row of short spines on the posterior margin. The dactylos is longer than 

 the pollex, smooth on both margins, except for a few delicate hairs near the base, and 

 slightly curved posteriorly. 



The fifth pair of pereiopoda (o) is shorter than the preceding, which is due to the three 

 last joints being each slightly shorter than their homotypes in the preceding pairs, more 

 especially the dactylos, which is thicker and shorter and sub-lanceolate, there being no 

 polliciform prolongations to the propodos. This pair is simple in the male, the only sex 

 with which we are acquainted. 



The first pair of pleopoda (p) is biarticulate, the first joint being a three-sided stem, 

 which, when pressed against the ventral surface, lies compactly in a curved groove formed 

 between the ventral surface of the pereion and the projecting inferior margin of the 

 carapace. This joint reaches as far as the coxa of the posterior pair of pereiopoda, where 

 it articulates with the second, which is narrow at the base, and at a short distance from 

 it suddenly widens into a long, hollow, spatuliform organ, the distal extremity of which 

 reaches as far as the coxa of the third pair of pereiopoda. This form only exists in the 

 male ; and, from its position and relative proportions, it undoubtedly fulfils an effective 

 purpose. But of this I shall be enabled to speak more fully when writing of another 

 species which I have had better opportunities of examining. 



The second pair of pleopoda (g) is biramose, the two branches being foliaceous, narrow, 

 flattened, flexible, tapering, and fringed at the margin with fine hairs ; the inner ramus 

 near the base supports two stylamblydes of unequal length, the longer of which is 

 furnished with two or three rather obscure cin'cinnuli. 



The third, fourth, and fifth pairs of pleopoda resemble the second except in having 

 only one stylamblys instead of two. 



The sixth pair articulates with the posterior margin of the sixth somite of the pleon ; 



