1899,] CRUSTACBAKS PROM LAKE TANGANYIKA. 705 



upper edge, three (rarelv two) of which are behind the orbit. The 

 teeth become more widely spaced distally, and the last one is gene- 

 rally separated by rather less than half the length of the rostrum 

 from the simple, sharply pointed tip. The lower margin of 

 the rostrum bears from 10-20 teeth, which extend quite to the tip. 

 Below the orbit the anterior margin of the carapace is produced 

 into a triangular tooth, but there is no " antennal " spine such as 

 is present in most species of Caridina, e.g. in C. ivi/cMi (PL XXXIX. 

 fig. 3.). A little way back on the side of the carapace, and below 

 the level of the sub-orbital tooth, there is a well-marked " hepatic" 

 spine. The lower anterior corner of the carapace is evenly rounded, 

 and there is no pterygostomial spine. 



The peduncle of the antennules (PI. XXXIX. fig. 4) falls short 

 of the distal tooth on the outer margin of the antennal scale. The 

 first joint is about equal in length to the two succeeding joints to- 

 gether. The basal spine is small and slender, its tip falling short 

 of the distal end of the jomt by | the length of the joint. The 

 short spine on the distal end of the first joint reaches to about ^ 

 the length of the succeeding joint. The ocular peduncle is rather 

 shorter than the first joint of the peduncle of the antennule. 



The mandibles (PI. XXXIX. fig. 5) are somewhat dissimilar on 

 the two sides. The cutting-edge is separated from the molar 

 process by a shallow emargination, within which are set two stout 

 setse (in C. ivyckii there is a row of about ten), followed at a little 

 distance by a thick brush of finer setse just in front of the molar 

 process. 



The first maxillae (PI. XXXIX. fig. 6) differ from those of 

 Caridina, and such allied genera as Atya and Atyaephyra, in the 

 smaller size of the two inner lobes, the inner edges of which are 

 much shorter, while the lobe which in these genera represents the 

 exopod is here absent. 



The second maxillae (PI. XXXIX. fig. 7) also depart somewhat 

 from the type characteristic of the Atyidce. In the other members 

 of the family the middle lobe of the endognath (the proximal 

 division of the lacinia externa in Boas's nomenclature) is very much 

 expanded, overlapping both the other lobes and presenting a very 

 long, straight, inner edge. In the present form this lobe is much 

 smaller, its inner edge being hardly longer than that of the distal 

 lobe, which it does not overlap. The proximal lobe, as in the other 

 Atyido', is large and is overlapped for a short distance by the middle 

 lobe. The scaphognathite is truncated anteriorly and produced to 

 a point posteriorly, where it bears, as usual in this family, a tuft of 

 very long slender setae, hooked at the tip but not presenting the 

 curious swelling and tooth near the base which characterize these 

 setae in C. ivyclii. 



In the first maxilliped (PI. XXXIX. fig. 8) the exopod tapers 

 gradually from the base with hardly an indication of the external 

 lobe (marked a by Boas) present in Caridina as in most EuTcyphota. 

 The epipod, rudimentary in Caridina, seems to be quite absent. 



The third maxillipeds (PI. XXXIX. fig. 9) extend forward as 



