256 Mr. W. F. Lanckester on some 



17. Potamon (Geothelpkusa) Burgeri,de Man. 



Potamon (Geothelpkusa) Biirgeri, de Man, Notea Leyd. Mus. vol. xxi. 

 pts. i.-iii. pp. 121-127, pis. xi., xii. fig. 14 (1899). 



Distr. Mount Liang Koeboeng. 



No. XCV. Hab. Kuching. 



A female example, quite agreeing with Dr. de Man's 

 description of a male, except in regard to the following 

 points : — The left chelipede is the larger, and not the right ; 

 the fingers, moreover, which on the right side meet all along 

 their length, are somewhat widely separate on the left. The 

 nasogastric groove is continued faintly on to the front, and 

 shows a tendency to bifurcation behind ; there is also a 

 faint oblique depression between the gastric and branchial 

 regions on each side. 



Dim. : Greatest length 15*5 millim., greatest breadth 21. 



18. Potamon (Thelphusa) hidiense, sp. n. 

 (PI. XII. fig. 3.) 



No. CCCLXXVII. Hab. With this specimen I have the 

 following note from Mr. Shelford : — " Caves at Bidi in pools; 

 the caves were absolutely dark. Body pale brown, legs 

 white." 



A male. This form is closely related to one obtained by 

 Dr. de Man from the Dutch Expedition to Central Borneo, and 

 named by him P. Melanippe, which is itself allied to P. Aus- 

 tenianwn, a form described by Wood-Mason from Assam. 

 Like them, this specimen is most noticeable for the length and 

 slenderness of its legs ; but the penultimate pair are a little more 

 than three times as long as the carapace, and their meri are also 

 longer than the carapace by nearly a fifth of their length. In 

 this, too, they differ from P. Melanippe in that the meri of the 

 last four legs are armed with a small blunt spine anteriorly, 

 quite close to the distal end. The external maxillipeds are 

 precisely similar to those of P. Melanippe ; the chelipedes, too, 

 are essentially similar, except that the fingers do not quite 

 meet along their length and their tips decussate. The shape 

 of the male abdomen is, however, quite different : the sixth 

 segment is indeed quite similar to that of P. Melanippe ; but 

 the fifth, instead of being narrower at its base than at its 

 extremity, is, if anything, ever so little broader, with its 

 sides straight and practically parallel ; as a consequence of 

 this, the transition from the narrower terminal to the broader 

 basal segments is much less marked than in Dr. de Man's 

 form. 



