648 THE VOYAGE OF H.M.S. CHALLENGER. 



First GnathojMch with a short triangular wrist, a very robust oblong hand, with the 

 palm at right angles : subchelate. 



Second Gnaihopods weak, feebly chelate. 



Perseopods all with the nail very short ; perseopods of the last three pairs short, 

 the first joint of the last pair greatly dilated. 



Uropods short, successively decreasing, inner ramus of the last pair almost 

 rudimentary. 



Telson short, broad, entire. 



Reraarks. — The generic name is chosen to call attention to the relationship between 

 this genus and Onesimus, Boeck. In assigning only " 5-6 " spines to the apex of the 

 palp of the first maxillae Boeck unduly limits the number, as there are more in Onesimus 

 edwardsii (Kr0yer). 



Onesimoides carinatus, u. sp. (PL XIV.). 



Rostrum, rudimentary, lateral lobes of the head produced not far in a rounded angle ; 

 a carina scarcely perceptible on the first five perseon-segments, well-marked on the sixth 

 and seventh of the jDerseon and the first four of the pleon ; the fourth segment of the 

 pleon with a dorsal depression, the sixth outdrawn on either side of the telson ; all parts 

 furred with short hairs ; a slight dorsal depression on the segments from the fourth of 

 the perseon to the third of the pleon gives a crenate appearance to the dorsal outline ; 

 the postero-lateral angles of the third pleon-segment are right angles. 



Eyes not made out. 



Uppjer Antennse. — First joint of the peduncle much longer than broad, with a 

 dorsal depression near the base, and many minute feathered cilia along the upper margin ; 

 second and third joints short ; flagellum of twelve joints^ the first nearly as long as the 

 first of the peduncle or as five of the following joints of the flagellum ; this joint tapers 

 distally, and so does the flagellum as a whole, although all its joints except the first and 

 last widen a little distally ; the secondary flagellum of four joints, of which the last 

 minute, the first as long as the first of the primary, close to which it lies, spreading out a 

 broad thin membrane over the numerous rows of slender cylinders which form the 

 brush ; on the under side of this shield are five or six sets of cilia singly or in groups. 



Lower Antennse quite free from the side-plates of the perseon ; rather shorter than 

 the upper antennse ; the first joint not greatly expanded, partly covered by the projecting 

 lobe at the lower front angle of the head ; gland-cone very prominent ; third joint short ; 

 fourth joint a little expanded distally, rather longer than the fifth, nearly as long as 

 the first joint of the upper flagellum ; flagellum of nine joints. 



Lower lobe of the epistome projecting a little in front of the upper lip. 



Mandibles. — Cutting edge folded back in the specimen so that its contour could not 



