lis ME. T. SCOTT ON EXTOIMOSTEACA 



Last, joint of the posterior antennEe fully three-fourths the length of the precetlinp^ 

 joint. Mouth-organs similar to those of Oiicaa ohtusa, except that the last joint of the 

 posterior foot-jaw is broadly ovate; the fringe of hairs on the inner margin extends 

 backwards from the apex nearly three-fourths the length of the joint, and is bounded at 

 the proximal end by a small spine (fig. 16). The swimming-feet are similar to those of 

 Onccea ohtusa, but the joints, especially of the outer branches of the first pair, are 

 jiroportionally longer, and the length of the terminal spines of both branches of all the 

 swimming-feet is much greater than those of that species : in the iiist pair the terminal 

 spine of the outer branches is equal to the combined length of the second and last joints ; 

 in the fourth pair the terminal spines of both branches are equal to the entire length of 

 the branches they spring from ; the terminal spines of the inner branches are also serrate 

 on both branches. The fifth pair, like those of Onccea ohtusa, are very small and rudi- 

 mentary. One or two females only of this species were obtained. 



Habitat. Station 9, 50 fathoms, collected January 10th. Lat. 1^ 55' 5'' N., long. 

 5' 55' 5" E., 300 ftithoms, collected January 22nd. 



This species, though closely resembling Onccea ohtusa, appears to be quite distinct 

 from it ; the following are some points in which it differs from that species : — the last 

 joint of the secondary branch of the posterior antennae is considerably longer ; the joints 

 of the outer branches of the first swimming-feet are proportionally longer ; the abdomen 

 is shorter, being only equal to about two-fifths of the length of the cephalothorax ; and 

 the terminal spines of the swimming-feet, and especially of the fourth pair, are of much 

 greater length than those of Onccea ohtusa. Onccea mecliterranea (Claus) seems to agree 

 much closer with this species than with Onccea ohtusa (Dana), and I have therefore 

 ascribed it to the species described by Dr. Claus. 



Genus Hersiliodes, Canu, 1888. 



Hersilioees LiviNGSTONi, n. sp. (PI. XIII. figs. 31-38.) 



Length, exclusive of tail-setse, 1-03 mm. Viewed dorsally the body is broadly ovate, 

 and much constricted near the posterior end ; it is composed of six segments, the first 

 being nearly equal to the entire length of the other five ; the fifth segment is short, and 

 considerably narrower than that which precedes or follows it ; the breadth of the last 

 segment is greatest posteriorly. Forehead rounded. Anterior antennae stout, 7- 

 jointed, and bearing numerous setiB; the proportional lengths of the joints are nearly as 



shown in the formula : — 



15 . 25 ■ 12 . 18 . 14 . 11 . 11 



12 3 4 5 6 7 ■ 



Posterior antenniie stout, 4-jointed, the first joint being nearly equal to the 

 combined length of the other three; the third joint bears two stout curved spines at the 

 exterior distal angle, while the truncate extremity of the last joint is armed with four 

 elongate curved sj)ines and a few setse (fig. 33). The mouth is in the form of a small 

 conical tube, the margin of which is fringed with cilia. The mandible is armed 

 exteriorly with a stout, somewhat curved tooth, having a doul:)le row of scrratures along 



