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



flagellum is long and thick, and seemingly little flexible. The secondary flagellum of 

 four joints together is shorter than the first of the primary. 



Loiver Antenna?. — Gland-cone very prominent, third joint short, fourth and fifth 

 subequal in length, with some cilia on the upper and setae on the lower margins ; flagellum 

 of fifty- three joints, rather thinner and longer than that of the upper antennse, the 

 calceoli equally numerous, placed on the upper margin confronting those of the upper 

 antennse, but in both pairs so placed that, while the calceoli of alternate joints are seen 

 full face, those of the other alternate joints will be seen in profile. 



Epistome a little prominent. 



Mandibles. — Cutting edge evenly convex, with a tooth at the top, the lower apex 

 scarcely indented ; secondary plate of the left mandible small, curved ; spine-row of 

 three small spines, behind these a long tract of fur leads to and partially lines the molar 

 tubercle, the crown of which is minutely denticulate, strongly directed backwards, and 

 carrying a furry tuft above ; the palp is set forward, over the front of the molar tubercle, 

 its first joint short, the second rather stout, with some five small spines on the inner 

 margin near the apex, and three or four along the upper half of the outer margiu ; the 

 thii'd joint much curved, a short piece of its inner margin clear, the remainder fringed 

 with eight and twenty spines, the first twenty- one pectinate on the upj)er border, the 

 other seven longer, near and at the apex, pectinate below ; a single long spine or seta 

 near the outer margin close to the base. 



Lower Lip. — Apical margins of the forward lobes broad, somewhat squared, much 

 ciliated, little dehiscent. 



First Maxilla?. — Inner plate small, with two unequal plumose setge on the apex ; 

 outer plate with very oblique apical margin ; of the eleven spines that which stands 

 inmost has seven marginal teeth, the next above it four ; these are somewhat isolated ; 

 of the rest the outer are the stoutest, with one, two, or three marginal teeth ; one about 

 central has seven ; the second joint of the palp has six or seven small teeth on the apex 

 and one spine or short seta ; below the palp the shaft has on its outer border some 

 groups of long setae. 



Second Maxillae. — Outer plate decidedly longer than the inner ; the long curved 

 spines on its apical border are followed by a row of small ones continued some little way 

 down the outer border ; on the inner plate the spines and setse of the very oblique 

 apical border are terminated by a long plumose seta. 



Maxillipeds.— Inner prismatic^ plates broad, reaching nearly to the apex of the first 

 joint of the palp, the plumose setse in the usual position, the apical border almost 

 squared, with three close-set teeth, followed by four curved spines decreasing in size as 



' The epithet prismatic was applied to these plates first, I believe, hy Kr0yer ; it refers to that which an unshaded 

 diagrammatic drawing cannot show, namely, that to a spectator looking upon the inner surface of the maxillipeds 

 the inner edges of these plates are almost invariably nearer, sometimes much nearer, to the eye than their outer edges. 



