244 A. Alcock —Carcinological Fauna of India. [No. 2, 
Mithrax spinifrons, A. Milne-Edwards, Ann. Soc. Ent., France, (4) VII. 1867, 
p. 263. 
Mithrax ajfinis, F. de B. Capello, Jorn. Sci., List)., 1870-71, p. 264, pi. iii. figs. 
4, 4a, 
Mithrax ( Schizophrys) affinis, triangularis (et varr. excipe var. dichotomy) 
Kossmann, Reise Roth. Meer., Crust., pp. 11 and 13; and Schizophrys triangularis 
var. indica , Richters, Mobius, Meeresf. Maurit., p. 143, pi. xv. figs. 8-14. 
Carapace pyriform, its greatest breadth about T % its length behind 
the point of bifurcation of the rostral spines, its surface closely and 
unevenly granular, with scattered sharp tubercles in addition. Exclu¬ 
sive of the large unequally-bifid post-ocular spine, the antero-lateral 
border is armed with six equidistant spines, the last of which is the 
smallest and is situated on a rather higher level than the others: the 
posterior border proper is generally beaded, and has its angles pro¬ 
duced and upturned. 
The rostrum consists of two stout parallel or incurved spines, the 
length of which is from one-fifth to one-sixth that of the carapace pro¬ 
per, and the outer border of each of which carries a strong accessory 
spine. 
The basal antennal joint ends in two stout spines, and there is a 
spine on the sub-hepatic region outside the angle of the buccal frame, 
and a sharp denticle in the middle of the inferior border of the orbit. 
The chelipeds vary: in both sexes the palm is long — twice the length 
of the fingers — smooth, polished, and either quite unarmed, or armed, 
at the near end of the upper border, with a spine or with two or three 
denticles; and in both sexes the merus and carpus are either spiny or 
granular. 
But whereas in old males the chelipeds are stouter than any of 
other legs, are more than half again as long as the carapace and rostrum 
and nearly half again as long as the 2nd pair of legs, and have deeply 
channelled fingers that meet in less than their distal half ; in females 
and young males they are not stouter than the other legs, are not quite 
equal in length to the carapace and rostrum or to the second pair of 
legs, and have the fingers less deeply channelled, and apposable in at 
least half their extent. 
The ambulatory legs decrease very gradually in length : they have 
short claw-like dactyli, and the merus is armed at the far end of the 
upper border with a spine or tubercle. The body and legs are hairy, 
and the animal frequently protects itself with flat pieces of Nullipore, 
&c. 
In the collection is a large series of specimens from all parts of the 
Indian coast, from Mergui and Tavoy on the East to Karachi on the 
West. 
