REPORT ON THE CRUSTACEA MACRURA. 851 



armed on the upper and lower margins with long stout articulated spines. Frontal 

 margin having the orbit defined by an inner and an outer canthus. First and second 

 antenna] teeth strong and well developed. Fronto-lateral angle rounded. 



Pleon dorsally smooth and round ; sixth somite scarcely longer than the fifth. 



Telson longer than the sixth somite, dorsally flattened, and laterally armed with 

 minute spinules ; posterior extremity produced to a sharp point furnished on each side 

 with movable spines or hairs. 



Ophthalmopoda pyriform, uniarticulate, and near together. 



First pair of antennae having a strong stylocerite, and terminating in two long and 

 slender flagella. 



Second pair of antennas furnished with a pointed scaphocerite aud carrying a long and 

 robust flao-ellum. 



O 



First pair of gnathopoda terminating in a duplex joint. 



Second pair of gnathopoda six-jointed, long, slender, and pediform. 



First two pairs of pereiopoda long, slender, and chelate ; the carpos long, the palm of 

 the propodos short, and the pollex and dactylos long, slender, and styliform. Posterior 

 three pairs robust, having a sharp carpos, a long propodos, and a short dactylos. 



Pleopoda biramose, the first pair having the inner branch short and the posterior pair 

 broad and subequal in length with the telson. 



Geographical Distribution. — The first specimens were taken on the 15th of July 

 1374, near the Kermadec Islands in the Pacific, another was taken near the Admiralty 

 Islands, and the third, being the type on which A. Milne-Edwards founded the genus, 

 was taken by Professor Agassiz off St. Domingo. The average range of depth is between 

 400 and 500 fathoms. 



Stylodactylus discissipes, n. sp. (PI. CXXXVIII. fig. 1). 



Carapace quite one-third of the length of the animal ; posterior dorsal surface smooth 

 and round ; frontal region compressed to a carina that is not elevated above the cara- 

 pace, and produced anteriorly to a laterally compressed rostrum that is slightly elevated 

 at the extremity, and armed on the upper surface with thirty strong and robust spines 

 that articulate with the rostrum, the posterior standing on the gastric region, and the 

 anterior near the apex. First and second antennal teeth well developed. 



Pleon having the third somite not arcuate and not longer than the preceding ; sixth 

 somite subequal with the fifth. 



Telson shorter than the two preceding somites, and corresponding in length with the 

 inner plates of the rhipidura, dorsally flattened, and armed at the dorso-lateral angles 

 with five spinules, and terminating in a short central point and seven spines. 



Ophthalmopoda short and pyriform ; ophthalmus brown in colour. 



