182 



The legs decrease slightly in stoutness, and increase in length, from the 

 1st to the 4th, which, in the male, is as long as the carapace and first 2\ abdo- 

 minal somites combined and is about a third of a dactyl-length longer than the 

 5th pair. In the female the 4th pair are only as long as the carapace and first 

 2 abdominal somites combined, and are at least a dactyl -length longer than the 

 5th pair, which in this sex are almost perfectly chelate. In the first 3 pairs the 

 propodite is compressed and broadened, especially in the case of the 8rd pair 

 of the female : in the 4th and 5th pairs the propodite is long and subcylindrical, 

 that of the 4th pair being more than three-fourths the length of the merus. 



In the male the appendages of the 2nd abdominal somite are biramous, 

 both rami being falcate-foliaceous, and those of the 3rd-5th somites are rudi- 

 mentary in the adult though distinct enough in the young. 



In the female the appendages of the 2nd abdominal somite are biramous, 

 both rami being broadly foliaceous, and those of the 3rd-5th somites are biram- 

 ous with the outer ramus foliaceous and the inner slender and 3-jointed. 



In an egg-laden female, the carapace is 31 millim. long. 



Bay of Bengal, off Madras coast, 91 fathoms: Arabian Sea, off Calicut, 

 100 fathoms. 



4254-4250 3380-3386 



Regd. No. 



10 



107. ArctUS rilbeilS, Alcock and Anderson. 



Arctus rubens, Alcock and Anderson, Journal Asiatic Soc. Bengal, Vol. LXIII, 1894, pt. 2, p. 165. 



Carapace, measured in the middle line, not much longer than the first 5 

 abdominal somites, its lateral margins serrated and cut into 3 lobes : it is dorsally 

 traversed by 3 crenulate carinse, the middle one of which is salient and is cut 

 into two lobes by the cervical groove, the lateral ones being not very prominent 

 except at the inner orbital angle where they end each in a strong tooth. The 

 branchial regions outside the lateral carinas are beset with numerous squamiform 

 tubercles, and there are some similar tubercles on the gastric region and along 

 the course of the branchio-cardiac grooves. The posterior border, which is 

 separated from the rest of the carapace by a deep groove, is deeply notched in 

 the middle line. The thoracic sternum is concave, but not deeply so, and each 

 of its segments carries a strong median tubercle. 



There is some squamiform sculpture on the abdominal terga (especially on 

 the 6th) and pleura. The abdominal terga 2-5 are longitudinally carinate, the 

 carina? of the 2nd and 3rd being deeply notched posteriorly, those of the 4th 

 and 5th being produced posteriorly to form a blunt claw-like tooth. 



Less than half the 3rd joint of the antennular peduncle projects beyond the 

 antennas. 



