290 
THE TANGANYIKA PROBLEM. 
The telson (Fig. 18) is about as long as the inner plates of the uropods, with 
straight sides, tapering to the obtusely pointed tip which bears four spines, two 
short external and two longer internal, between which latter spring three plumose 
setee. On the dorsal surface of the telson are two pairs of spinules. In C. wyckii 
the tip of the telson bears eight spines, and the dorsal surface three pairs of 
spinules. 
The gills are four in number on either side, three pleurobranchs, corresponding 
to the second, third and fourth peneopods, and one which I believe to be a pleuro- 
branch (though it is difficult to determine the precise point of insertion) above the 
first peraeopod. There are no epipods on the maxillipeds or peneopods, unless we 
regard as a rudimentary epipod the small papilla at the base of ttie third maxilliped 
described above. In tabular form the arrangement is : — 
1 
Mxp.® 
Mxp. 3 
Per. 1 
Per.® 
Per. 3 
Per. 4 
Per.* 
Pleurobranchiae 
Podobranchiae 
Arthrobranchiae 
1 
1 
1 
1 
... 
... 
4 
4 
The statements of various authors as to the branchial formulae of the genera 
of Atyidce are somewhat conflicting, but all agree in giving a larger number of gills 
and a complete series of epipods as far as the fourth peraeopods. 
In C. wyckii and C. typus I find the following arrangement : — 
Mxp.® 
Mxp. 3 
Per. 1 
Per.® 
Per. 3 
Per. 4 
Per.* 
Pleurobranchiae 
Arthrobranchiae 
Podobranchiae 
1 
2 
ep. 
1 
1 
ep. 
1 
ep. 
1 
ep. 
1 
ep. 
1 
This agrees with the formula for Atya. Claus states that Troglocaris lacks the 
arthrobranch of the first peraeopod. According to Boas, Atyccphyra desmarestii has 
no arthrobranch on the first peraeopod, and only one on the third maxilliped. 
The males are usually somewhat smaller than the females, and have as usual the 
pleural plates of the abdomen less deep. In the female the two flagella of the 
antennule are of about equal length, and about twice as long as the peduncle, the 
outer flagellum being slightly thickened for about two-thirds of its length. In the 
male both flagella are much elongated, the outer being longer than the inner, and 
