TUBICOLOUS AMPHIPOD — CHILTON. 
3 
In large sized males the lower antennae are stouter and more 
pediform than in younger specimens, and the long setae are by no 
means so conspicuous. 
The mouth parts appear to correspond closely with Stebbing’s 
description, but I have not examined them in great detail. 
The first gnathopoda are the same in both sexes and agree with 
Stebbing’s description as closely as can be expected when allowance 
is made for individual variation. 
The second gnathopoda differ very much in the two sexes. In 
the female they do not differ very greatly from the first gnathopoda 
and agree very closely with the description already given by Mr. 
Stebbing. I give a drawing for the sake of comparison with the 
second gnathopoda of the male, (see fig. gn. 2%). In the male the 
second' gnathopoda differ considerably from those of the female 
and also differ very much at different stages in the development of 
the same individual. The form most commonly met with is that 
shown in fig. gn. 2 B , which represents the second gnathopod 
of a moderate sized male ; it will be convenient to describe this first. 
The first free joint, the basos , is narrow at the base where it 
articulates with the moderate sized side-plate but rapidly widens 
until at the widest part it is more than half as broad as long ; the 
anterior edge is straight except near the base and is fringed with 
about ten spinules, the posterior margin is strongly convex and 
bears two or three setae at the apex; the ischios and the meros 
are of the usual shape and not unlike those of the female ; the 
meros has the distal extremity produced, rounded and tipped with 
a few seta; ; the carpus is very large and broad, its anterior mar- 
gin very convex especially towards the base, a small group of seta?* 
at its distal extremity, the posterior margin is indistinctly serrate 
and bears five groups of long setae in the serrations, other shorter 
set<e are situated between the serrations and a few on the surface 
of the joint ; the postero-distal corner is produced acutely and 
reaches about half way along the inner margin of the propodos, 
and between this corner and the inner articulation of the propodos 
is a short rounded lobe reaching only about half as far. The 
propodos is considerably shorter than the carpus, rather more than 
twice as long as broad, the anterior margin curved and bearing 
about six spinules, that at the apex the longest ; the posterior 
margin with the basal half smooth, but the distal half minutely 
serrate or more strictly speaking crenate, the whole margin fringed 
with abundant long seta?, a few others being situated along the 
surface of the joint ; the dactylos is like that of the female and 
has the inner margin denticulate towards the distal end, but the 
inner margin of the terminal tooth again is smooth. 
* These serrations are not shown very distinctly in the plate. 
