404 A. Alcock — Garcinological Fauna of India, [No. 3, 



The 2nd and 3rd pairs of legs are about 1± times, the 1st pair are 

 not quite If times, and the 4th pair are are not 1£ times, the length of 

 the carapace: on the anterior border of the merus of the first three 

 pairs is a subterminal spine. 



The sidewall of the carapace and the basal joints of the legs have 

 little tomentum. 



In the Indian Museum are 2 males and an egg-laden female from 

 " the Bay of Bengal " and 2 young females from Upper Tenasserim. 



The carapace of the largest male is 19 millim. long and not quite 20 

 millim. in its greatest breadth. 



91. Ptychognathns onyx, n. sp. 



Very closely related to P. spinicarpus, Ortni., and to P. Polleni and ajfinis, de M., 

 if these species are distinct. 



This species very nearly resembles P. dentata, from which it differs, 

 young males being compared with females of the same size, only in 

 the following particulars : — 



(1) the carapace though otherwise similar is much thinner and 

 more depressed and its markings are not quite so distinct : 



(2) in the middle of the anterior border of the buccal cavern is 

 a slight prominence, but no distinct tooth : 



(3) the exognath (in the young male) is, as in the female of 

 P. dentata, but little broader than the ischiognath : 



(4) in the chelipeds of the young male the inner angle of the 

 wrist is produced to form a long spine ; there is no hair on the inner 

 surface of the palm, but on the outer surface, in the finger-cleft and 

 extending along the fixed finger, there is a tuft of hair ; the outer sur- 

 face of the palm also, as in the female of P. dentata, is traversed, close 

 to the lower border, by a raised line, which runs to the tip of the fixed 

 finger ; finally the fingers are blunter, and the dactylus is only about 

 twice as long as the upper border of the palm. 



Practically the chief distinction between this species and 

 P. dentata is that in the male of this species the inner angle of the wrist 

 forms a long spine, and the hair is on the outside instead of on the 

 inside of the hand. 



In the Indian Museum are two young males probably from Tavoy. 

 The carapace is a little over 12 millim. long and 13 millim. broad. 



92. Ptychognathus andamanica, u. sp. 

 Closely related to P. pusilla, of which it may be an Andaman variety. 

 Carapace not much broader than long, quite flat, much depressed, 

 the regions are hardly indicated, even when the carapace is quite dry, 



