420 A. Alcock — Carcinological Fauna of India. [No. 3, 



not very deep, its free margin strongly sinuous. Lateral borders of the 

 carapace nearly parallel, armed with one acute tooth behind the acute 

 outer orbital angle. 



The chelipeds are similar in the two sexes, except that they are 

 a good deal more massive and more sharply sculptured in the male. 

 They are not quite twice the length of the carapace : the outer surface 

 of the arm and wrist are granular-rugose, the outer surface of the 

 palm is granular, and there is a transverse granular ridge on the inner 

 surface of the palm : the upper border of the arm is crest-like and ends 

 in a sharp tooth, and the distal end of the inner border forms an acute 

 angular serrate lobe : the inner angle of the wrist is dentiform : close 

 to and nearly parallel with the upper border of the palm runs a fine 

 and very finely and evenly pectinate crest : along the upper border of 

 the dactylus runs a very elegantly milled crest of from 40 to 60 fine 

 teeth. In the male the palm is at least as high as long, the fingers 

 meet only at tip, and the dactylus is about twice the length of the 

 upper border of the palm. 



The meropodites of the legs are foliaceous, but their greatest 

 breadth is not quite half their length : there is a sharp subterminal 

 spine on their anterior border only. The dactyli of the legs are two- 

 thirds, or more, the length of the propodites. The 3rd pair of legs, 

 which are the longest, are a little more than twice the length of the 

 carapace. 



In the Indian Museum are 9 specimens, from Mergui, the Anda- 

 mans, and Penang. The carapace of a large specimen is nearly 38 

 millim. long and nearly 40 broad. 



106. Sesarma tetragonum (Fabr.). 



Cancer tetragonus, Fabricius, Ent. Syst., Suppl. p. 341. 

 Cancer fascicular is, Herbst, Krabben etc. III. i. 49, pi. xlvii. fig. 5. 

 Sesarma tetragona, de Man, Zool. Jahrb., Syst., II. 1887, p. 646 : Henderson, 

 Trans. Linn. Soc, Zool., (2) V. 1893, p. 392. 



This- species closely resembles S. tseniolatum, from which it differs 

 in the following characters : — 



(1) the carapace is slightly broader : 



(2) the subterminal lobe of the inner border of the arm is smaller, 

 while the tooth at the inner angle of the wrist is more pronounced : 



(3) the fine striated crest along the upper border of the palm is 

 shorter : 



(4) the crest of the upper surface of the movable finger of the 

 chelss is coarsely crenulate. 



