388 ME. J. E. HEKDEESON— A CONTEIBTJTION 



Tuticorin {Thurston). Common at Madras {J. B. S.). 



This is a smaller species than the foregoing, and distinguished at once by the absence 

 of a stridulating ridge from the chelipedes in both sexes. It is a terrestrial crab and 

 lives in burrows at some distance from the sea. 



Distribution. From Mauritius and the Seychelles to China, Australia, and the Pacific 

 (New Caledonia, New Hebrides, Eijis, &c). 



Genus Gelasimtjs, Latreille. 



144. Gelasimtjs annulipes, Latr. 



G. annulipes (Latr.), De Man, Mergui Crust., p. 118, pi. viii. figs. 5-7 (1887), ubi synon. 

 (= G. per -plexus, Mihie-Echr. ; G. pulchellus, Stm.). 



Eameswaram and Tuticorin {Thurston). Abundant on the margins of the South 

 Indian backwaters, burrowing in sand or mud {J. B. S.). 



A curious sexual difference has been pointed out by De Man, viz. the infra-orbital 

 ridge is simple and finely crenulated in the male, whereas in the female the crenulations 

 are larger, and in addition there is an accessory row of acute granules parallel to the 

 ridge, but placed within the orbital cavity. 



An adult male from Eameswaram has the carapace 12 mm. long and 21 mm. broad at 

 the level of the external orbital angles; the hand of the larger chela 38 mm. long. 



Distribution. From E. Africa to the Pacific (Tahiti and the Fijis). 



145. Gelasimtjs triangularis, A. Milne-Edw. 



G. triangularis (A. Milne-Edw.), De Man, Mergui Crust, p. 119, pi. viii. figs. 8-11 (1887). 



(=G. per plexus, Heller). 



Madras and Ennore (J. B. H.). 



This species is found living with G. annulipes at the above localties, and the two are 

 almost equally common. G. triangularis is, however, a slightly smaller species, and its 

 colour-markings are different, but I omitted to note these in living specimens. The 

 carapace is narrower posteriorly in the present species, and the larger hand has only 

 two oranulated ridges on the inner suface, while there are three in G. annulipes. The 

 immobile finger of the larger chela is acute at its distal end, whereas in G. annulipes it 

 is subtruncated, or almost bidentate, owing to the presence of an accessory tooth near the 

 apex. In the two species there is considerable variation, and varieties of both are 

 common in which the inner margin of both fingers is without any prominent teeth. 

 The females of G. triangularis lack the accessory orbital row of granules met with in the 

 females of the other species. 



Distribution. New Caledonia {A. Milne- Edioards) ; Mergui (De Man); Ceylon and 

 Madras {Heller). 



