1164 THE VOYAGE OF H.M.S. CHALLENGER. 



Upper Lip. — The distal margin evenly convex, with a small piece at the centre 

 smooth, between two tracts that are finely furred. 



Mandibles. — The cutting edge divided into five teeth ; the secondary plate on the 

 left mandible having four strong teeth, on the right mandible having an oblique 

 irregularly denticulate margin, with a small tooth at the upper, and a more prominent 

 one at the lower, end ; the spine-row of two broad spines distally tapering and strongly 

 denticulate and feathered ; the molar tubercle prominent ; on one edge of the dentate 

 crown on the right mandible were seen eleven teeth very distinct, not crowded, at one 

 corner a long plumose seta, and on the opposite side a small oval denticulate excrescence, 

 corresponding to the laminar process already noticed in some other species ; the first 

 joint of the palp a little longer than wide, widening distally ; the second joint two and a 

 half times as long as the first, with four spines, three of which are on the lower half and 

 very long ; the third joint very little shorter than the second, with five long feathered 

 spines on the distal half of the front margin, followed by three on the narrow apex. 



Lower Lip. — The principal lobes a little dehiscent, and like the inner lobes not very 

 strongly ciliated ; the mandibular processes divergent, rather long and narrow. 



First Maxillae. — The inner plate small, with a long apical seta ; the outer plate with 

 ten spines easy to count on the distal margin, whereas in Cerapus sismithi there are, I 

 think, certainly only nine ; of the ten in the present species five that are longer than the 

 rest have several minute lateral denticles, of the others three have a denticle on the outer 

 side ; the second joint of the palp has seven spine-teeth on the distal margin and four 

 submargiual slender spines. 



Second Maxillae. — The setae of the inner plate do not appear to descend the inner 

 margin so far as in Cerapus sismithi. 



Maxillipeds. — The inner plates not reaching so far as the distal end of the palp's first 

 joint, with setae passing from the inner margin across the distal angle, the distal margin 

 broad, with three spine-teeth and several feathered spines, a subapical spine-tooth on 

 the inner margin ; the outer plates reaching beyond the middle of the second joint of 

 the palp, having ten spine-teeth on the inner and oblique apical margins, successively 

 longer, the six on the inner margin also successively thicker, the apical four becoming 

 successively thinner ; the first joint of the palp more than half the length of the second, 

 its inner margin only half as long as the outer, carrying two spines ; the second joint 

 fringed on the inner margin with many long spines ; the third joint shorter than the first, 

 the margins nearly parallel, the apical part crowded with long spines ; the finger very 

 short, narrowing distally, the ungual spine on the apex rather longer than the basal part, 

 the two together rather longer than the third joint. 



First Gnathopods. — Side-plates small, a little broader than long, with two or three 

 spinules at the lower margin. The first joint all but free from the side-plate, much 

 longer than the hand or wrist, widening distally, the front margin concave, fringed with 



