62 Memoirs of the Indian Museum. [Vol. IV, 



The. eyes are not greatly expanded. The cornea is much broader than the stalk 

 and its greatest breadth is distinctly less than the length of the whole organ. The 

 corneal and peduncular axes are at right angles to one another and the anterior margin 

 of the ophthalmic somite is produced and at the apex truncate or slightly emarginate. 

 In very young specimens, about 30 mm. in length, the corneal index 1 is approximately 

 4' 5 ; it increases as the animal grows and is about J'O in examples between 80 and 

 90 mm. in length, while in the largest individual examined it is as much as 8 - o. The 

 antennular peduncle is shorter than the carapace excluding the rostrum. The mandi- 

 bular palp is composed of three segments. 



The outer margin of the merus of the raptorial claw terminates anteriorly in a 

 sharp tooth. The carpus is grooved and carinate externally and its dorsal keel is 

 furnished with two tubercles, of which the distal is often bilobed ; more rarely there 

 are three distinct tubercles. The merus is somewhat expanded at its distal end in the 

 adult male and bears three movable spines and a row of fine pectinations on the margin 

 opposed to the dactylus. The dactylus is provided with six curved teeth including 

 the apical one ; the external margin is obtusely angled at the base and is strongly 

 sinuous in both sexes. The proximal part of the dactylus is slightly swollen. 



The last three thoracic somites are furnished with sharp submedian and intermediate 

 carinae. The fifth somite is bilobed laterally and does not possess any spines on the 

 inferior margin. The anterior process consists of a very sharp antrorse spine ; the 

 posterior process, which is not so sharp, is directed straight outwards and is less than 

 half the length of the anterior. The two marginal lobes of the sixth somite are almost 

 equal in length, but the anterior is narrower than the posterior and is obliquely trun- 

 cate at the apex. Both lobes of the seventh somite are acute, but the anterior is very 

 much shorter and narrower than the posterior. 



There are four pairs of sharp longitudinal carinae on the first five abdominal 

 somites and three pairs on the sixth. On the 2nd, 3rd, 4th and 5th between the 

 submedian carinae there is a small elongated and transversely-notched median tubercle. 

 The following carinae end in spines : — 



Carinae. Abdominal somites. 



Submedian' 2 .. .. .. 4,5,6. 



Intermediate .. .. .. (2)3,4,5,6. 



Lateral . . . . . . (1)2,3,4, 5> 6. 



Marginal . . . . . . r, 2, 3, 4, 5. 



The telson bears a close resemblance to that of the species belonging to the quin- 

 quedentata group. The median carina is sharp and is very obscurely notched at the 

 base ; it terminates in a short spine which overhangs a single blunt tubercle. The 

 oblique rows of pits leading to the interspaces of the intermediate marginal denticles 

 are distinct and there is also a single longitudinal row on either side of the median 

 carina. The submedian, intermediate and lateral teeth are well marked and behind 



1 The corneal index :— the number of times the breadth of the cornea is contained in the median 

 length of the carapace, excluding the rostrum. (See p. 9.) 



% Very rarely, in large specimens, the submedian carinae of the third abdominal somite end in spines. 



