1895.] 



A. Alcock — Cardiological Fauna of India. 



217 



rostrum well developed, subcylindrical, parallel or divergent, and bearing 

 on the inner margin, near to the extremity, a small accessory spine or 

 spinule. Abdomen (in the male) distinctly seven-jointed; in the 

 female some of the segments may be coalescent. Eyes small, supra- 

 ocular eave very prominent, its antero-external angle sometimes pro- 

 duced to a spine : post-ocular lobe also very prominent, its edge un- 

 equally bi- or tri-lobed. Antennas with the basal joint enlarged, with 

 a spine or tubercle at the aatero-lateral angle, and sometimes with ano- 

 ther on the outer margin ; the flagellum either exposed, or partially con- 

 cealed in a dorsal view by the rostral spines. Merus of the external max- 

 illipeds distally truncated, with the antero-external angle little, if at all, 

 produced, and the autero-internal angle emarginate. Chelipeds (in the 

 male) slender and moderately developed, palm usually somewhat elon- 

 gated, fingers denticulated near the distal extremity, and having between 

 them when closed a small hiatus at the base. Ambulatory legs slender 

 and somewhat elongated, the first pair much the longest, with the 

 joints subcylindrical ; dactyli nearly straight. 



Key to the Indian species of Naxia. 



I. Armature of the carapace consisting almost entirely of large 



clean-cut spines N. hystrix. 



fl. Spines of the rostrum parallel to near the 

 tip : supra-ocular spine obsolete : mei'opodites 

 of the trunk-legs without a terminal spine N. hirta. 



II. Armature 

 of the cara- 

 pace con- 

 s i s t i n g 

 chiefly of 

 tubercles, 

 among 

 which 

 there are 

 sometimes 

 a few 

 coarse 

 spines. 



. Spines of 

 the rostrum 

 divergent 

 from the 

 base: supra- 

 ocular spine 

 present: 

 meropo- 

 di te s of 

 some of the 

 trunk-1 e g s 

 with a large 

 t e rminal 

 spine. 



Spines of the 

 rostrum con- 

 si derably 

 more than 

 half the 

 length of the 

 carapace : 

 supra-ocular 

 spine very<{ 

 large and 

 acute : mero- 

 podites of all 

 the trunk- 

 legs with a 

 terminal 

 spine : palms 

 long and 

 slender. 



fa. Rostral 



spines widely 

 divergent : no 

 large spines 

 on the bran- 

 chial or in- 

 testinal 

 regions N. taurus. 



. Rostral 



spines moder- 

 ately diver- 

 gent : several 

 large spines 

 on the bran- 

 chial regions 

 and in the 

 middle line of 

 ^ the carapace N. cerastes. 



. Spines of the rostrum con- 

 siderably less than half the 

 length of the carapace : supra- 

 ocular spine blunt : meropodites 

 of the last three pairs of trunk- 

 legs unarmed : palms short and 

 inflated , ]Sf. investigator! 



