THE TANGANYIKA PROBLEM. 
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of its length there is a deep excavation of the inner side, a little beyond which 
distally stands a stout curved spine ; a double row of strong toothed spines smaller 
than the preceding, and gradually diminishing in size, fringe the distal margin of 
the notch ; the oblique posterior or proximal margin is fringed with feathered or 
pectinate sefie. Beyond the notch, the inner margin of the joint bears a series of 
6-7 short spines leading up to the pointed apex of the limb. I am not aware that 
an arrangement similar to this is found in other Afyide. In C. wyckii there is only 
a very slight concavity of the inner margin of the joint, clothed with numerous 
spines and sette. 
The first pair of peneopods (Figs. 10, 10a) do not reach to the terminal joint of 
the third maxillipeds. The ischium and merus are short and subequal. The carpus 
is conical in shape, raiher more than one-half as broad as long, about equal in 
length to the merus, and slightly longer than the palmar portion of the hand ; it is 
slightly excavated distally on the inner side (Fig. 10a). The hand is long and 
narrow, the breadth being about one-third of the length. The fingers are slender, 
longer than the palm, spoon-shaped, but acutely pointed as seen from the side, 
instead of truncate as in C. wyckii. The opposed margins bear series of small 
stout spinules increasing in size towards the tip, but there is no strong terminal 
hook as in C. wyckii. The brushes of setee borne by the fingers are very scanty 
compared with those of C. wyckii. 
The second peneopods (Fig. 11) reach forward as far as the tip of the third 
maxillipeds. The ischium is a little longer than the merus and about equal to the 
carpus. The latter is cylindrical and only slightly wider distally. The hand is 
longer than the carpus by one-third the length of the latter, and its breadth is less 
than one-quarter of its length. The fingers are very’ long and slender, about twice 
as long as the palm, sharply pointed, and with scanty terminal brushes. 
The third pair of peraeopods extend beyond the third maxillipeds when turned 
forward, and the last pair fall short of them. The dactylus is one-third to two-fifths 
the length of the propodus. The dactylus of the last pair (Fig. 13a) is similar to 
the preceding two pairs, having only a slightly larger number of spines on its inner 
margin, the numbers being from ix to 15 in the case of the third and fourth 
peneopods, and from 16 to 19 in the last pair. In Caridina the dactylus of the last 
peneopods is longer and bears much more numerous series of spines than do those 
of the preceding two pairs. In a specimen of C. wyckii, for example, the dactyli of 
the third and fourth pairs bore seven and eight spines respectively, while the 
dactylus of the fifth pair was half as long again and had a row of 39 spines. 
In the female, the first pair of pleopods (Fig. 14) have the endopod rather 
slender, pointed, and more than half the length of the exopod. In the male 
(Fig. 151, the endopod is a short ovate leaflet about one-quarter the length of the 
exopod. In nearly all the specimens of both sexes the first pair of pleopods are 
turned forward, with the exopod lying above and external to the bases of the 
posterior perceopods. According to F. Muller (“Kosmos,” IX. 1881, p. 121), this 
is the position taken by these appendages in the living Atyoida, and he states that 
they serve to protect the entrance to the branchial chamber, the fringe of marginal 
sette acting as a sieve to exclude mud, &c. 
In the second pleopods of the male (Figs. 17, 17 a), the appendix masculina is a 
little shorter than the appendix interna, and bears a number of stout spines. 
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