AMPHIPODA OF THE BRITISH ISLES. 157 
branch as figured by Vejdovsky is very small and delicate, and 
can no longer be seen in his specimens now that they are 
mounted in Canada balsam, but the rest of the uropod is so 
similar that I think the fine inner branch must be present in the 
Marlborough specimen also. In this specimen, again, the telson 
can be seen in side-view only, but it is evident that the two 
hinder angles project a little and bear set, as shown by 
Vejdovsky, and I think the posterior edge between them is 
slightly emarginate. In connection with this point it is perhaps 
worth while drawing attention to the fact that Jurinac has 
described considerable differences in the telson in the two sexes 
of his Wiphargus croaticus, the male having the telson roundly 
indented (rather than cleft) for a third of its length only, while 
in the female the telson is sharply cleft to two-thirds of its 
length [37. pp. 12, 15, & 16, and pl. i. figs. 3 & 12]. In Cran- 
gonyx mucronatus, Forbes, again, the differences of the telson in 
the two sexes are quite startling; and I have recorded the fact 
that in Calliopius subterraneus, Chilton, the telson is rather 
more deeply emarginate in the male than in the female. 
The lower antenna is shown in figure 4,a.2. It was wanting 
in Spence Bate’s specimen ; the articulations between the joints 
of the peduncle are slightly oblique, just as in Cragonyx com- 
pactus, Chilton. 
The mouth-parts, so far as I have been able to examine them, 
are in minute agreement with those of the Prague specimens, 
the mandibles, second maxille, and maxillipedes being practically 
identical; the first maxillze I have not seen. 
The first gnathopod was described by Spence Bate as being 
larger than the second; and this character was made use of by 
Della Valle as a specific character for separating Crangonyx 
subterraneus, Bate, from C. compactus, Chilton. Vejdovsky has 
rightly shown that really the two gnathopoda differ only slightly 
in size, and that the second is actually the longer, though from his 
figures it appears that it is scarcely so stout in proportion ; the 
same thing is true of the Marlborough specimen, as may be seen 
from a comparison of figs. 4, gn.' and 4, gn... For an account 
of the peculiar split sete on the propoda of the gnathopoda, 
reference must be made to Vejdovsky’s paper ; they are present 
in the Marlborough specimen, but the specimen is very small 
and the details of them cannot now be made out. 
The large size of the fourth side-plate is a peculiar character, 
