171 



the cervical groove, only 1 + 2 + 1 spines, instead of 1 + 1 + 2 + 1. Behind the 

 cervical groove, the oblique groove that delimits the cardiac region on either 

 side is not flanked by spines. There is no spine at the frontal end of the eye- 

 stalk. 



The median carina of the 5th abdominal tergum culminates anteriorly in 

 an antrorse spine similar to, but smaller than, that of the 4th. 



There are two spinelets at the outer angle of the basal joint of the anten- 

 nular peduncle. 



In the large chelipeds there are no enlarged spines, but only spinules, on 

 the lower border of the merus ; the hand is hardly as long as the merus, and 

 the fingers are shorter than the carpus and not a fourth as long again as the 

 palm. 



In a large male the length of the carapace in the middle line is 52 millim., 

 of the abdomen, 70 millim., and that of the large cheliped is 141 millim. 



Colour in life rosy pink. 



Arabian Sea, 738, 824, 836 fathoms. 



T-, t AT 536 1961-1964, 2364 



Regd. Nos. — : — — : — . 



Pentacheles, Spence Bate. 



Pentacheles, Spence Bate, Ann. Mag. Nat. Hist. (5) II. 1878, p. 276, and Challenger Crust. Macrura, p. 143. 



Differs from Polycheles only in the following particulars : — 



The external maxillipeds carry a functional epipodite, and the epipodites of 

 the first four pairs of thoracic legs are independent plates, attached to the podo- 

 branchiae at base only, and ascending into the branchial chamber in normal 

 fashion. The epipodite of the external maxillipeds may be long or short, but is 

 never a mere rudiment as in Polycheles : similarly the epipodites of the legs are 

 of variable length, sometimes ascending a short way into the branchial chamber, 

 sometimes nearly reaching the roof. 



Key to the Indian species of Pentacheles. 



I. Posterior border of the carapace spinose : each orbital sinus is divided into 

 two parts by a serrated lobe stretching across from the inner border of 

 each ... ... ... ... ... ... P. Hextii. 



II. Posterior border of the carapace smooth : orbital sinuses simple, not 

 divided : — 



1. Both angles of the orbital sinuses are armed with a spine: the 



carina? of the abdominal terga are entire ... ... P. Beaumontii. 



