204 Dr. C. Chilton on 
arise at the base of this finger ; the terminal joint or finger 
is long, curved, ending acutely, and has its inner margin 
finely denticulate (see fig. 11). ; 
The first gnathopod in the female (fig. 12) has the side- 
plate almost square, the lower margin slightly convex, with 
a few minute sete ; the basal joint is long, about three times 
as long as broad; the ischium has a tuft of sete at the 
postero-distal angle; the merus is almost quadrangular and 
bears two small tufts of sete on the posterior margin near 
the distal end and a row of stouter sete parallel to the distal 
margin ; the carpus is slightly shorter than the propod and 
almost oblong, narrowing abruptly at its junction with the 
merus ; its anterior margin is very slightly convex and bears 
only two or three small sete, and there is another small tuft 
on the surface near the postero-distal angle; the propod is 
oval in outline, somewhat narrowed at the base; anterior 
margin regularly convex, with five or six short transverse 
rows of sete, the posterior margin bearing three similar rows, 
and there are also three or four rows on the surface of the 
joint; the palm is regularly convex, not well defined, but 
bearing one or two stout spines and small tufts of more 
slender setee near the point against which the end of tlie 
finger impinges, the rest of the palm towards the base of the 
finger bearing a few short sete; the finger is strongly 
curved, tapering gradually toan acute point, and when closed 
fits closely against the palm. 
In the young males the first gnathopod has the same 
character as that just described for the female. In the older 
males (fig. 13), however, the shape of the propod becomes 
considerably different. It is widest at the base, the palm is 
much longer, straight or slightly concave, and the hind 
margin proper becomes very short, and in place of bearing 
the typical transverse rows of sete 1s irregularly serrate; the 
anterior margin and surface of the propod bear tufts of sete 
similarly placed to those described in the female; the finger 
is more strongly curved, so that when closed there is a space 
between it and the palm. In the oldest males that I have 
been able to examine there is practically no trace left on the 
short hind margin of the transverse rows of sete. In other 
specimens, however, presumably not so mature, this posterior 
margin is longer and still bears some of the sete, though 
these appear to be becoming shorter and modified into the 
serrate surface found in the old specimens. In the female 
and in young males the hind margin occupies nearly one- 
half of the posterior, margin of the propod, while in the 
fully developed male it forms only about a fourth of that 
