103 



The second, or " post-antennular " carina, is a continuation of the spine at 

 the outer angle of the orbit : usually it is a mere buttress of this spine, but 

 sometimes it is continued to the posterior border of the carapace, and occasion- 

 ally (but not in any Indian species) it is entirely absent. 



The third, or " post-antennal " carina, is also very constant : it is a continua- 

 tion of the branchiostegal spine and runs towards the posterior border of the 

 carapace, which sometimes it reaches and sometimes does not nearly reach. 



Synopsis of the Indian species of Heterocarpus. 



I. The 6th abdominal somite is nothing like twice as long as the 5th and 

 is much shorter than the telson : 



1. None of the abdominal terga are in any way carinatcd or acutely 



produced posteriorly 



2. The 3rd abdominal tergum is bluntly carinated : 



i. Rostrum in the adult much shorter than the carapace 

 proper, armed dorsally with 3 or 4 teeth : the 

 branchiostegal spine does not nearly reach the base 

 of the antennal scale 



ii. Rostrum, even in the adult, as long as the carapace, 

 dorsally smooth except for a spine above the eye: 

 the tip of the branchiostegal spine reaches well 

 beyond the base of the antennal scale ... 



3. Some of the abdominal terga are sharply carinated and have 



some of the carina? produced posteriorly into overhanging 

 spines : 



i. The 3rd, 4th and 5th abdominal carinra are produced as 

 spines : none of the other abdominal terga are 

 carinated 



ii. The 3rd and 4th abdominal carina! are produced as 

 spines : the 1st abdominal tergum is faintly, the 

 2nd sharply carinated 



II. The 6th abdominal somite is twice as long as the 5th and as long as the 

 telson : the 3rd abdominal tergum has a hump-like cariua 



H. tricarinatus. 



H. gibbosus. 



H. lievigatus. 



H. Alphonsi. 



H. ensifer. 



H. \\'ood-Mafoni. 



58. Heterocarpus gibbosiis, Spence Bate. 



Heterocarpus gibbosus, Spence Bate, Challenger Crustacea Jlacrura, p. 634, pi. cxii. fig. 2 : Wood-Mason, Aaa. 

 Mag. Nat. Hist. (6) IX. 1892, pp. 368, 369, fig. 6. 



Rostrum in the adult about three-fourths the length of tin- carapace, 

 strongly recurved, continued nearly to the posterior border of the carapace ;i> 

 a very high compressed serrated carina : it is armed vent rally with numerous 

 (from 10 to 16) teeth which are more or less concealed by cilia, and dorsally 

 with 3 or 4 (usually 3) distant teeth which are much smaller than the six teeth 

 of its carapacial carina. (In the young the rostrum is much longer than the 

 carapace). 



