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



setfe, in agreement with the figure given by Goes himself. It seemed on the whole, 

 therefore, better to widen Boeck's definition of Hij)j)omedon than to add to genera 

 already, as many authors think, too numerous. 



Genus Cheirimedon, n. gen. 



Epistofne with an ascending lobe. 



Mandibles with the palp set far forward, just over the molar tubercle, the third 

 joint a little shorter than the second ; molar tubercle prominent. 



First Maxillee. with the inner plate carrying two plumose setse ; the palp not dilated, 

 with several teeth on the apical border. 



Second Maxillse with the outer plate rather longer than the inner, neither of the 

 plates armed far dowTi the inner margin. 



Maxilliyeds with the palp having none of its joints elongate, fourth joint unguiform ; 

 inner plate reaching as far as the apex of the first, outer as far as the apex of the second, 

 joint of the palp ; outer plate with well-developed teeth, two at the apex spiniform. 



Loiver Antennae with the peduncle elongate, fourth and fifth joints subequal. 



First Gnathopods with the wrist very short, hand large, distally dilated, subcheliform. 



Body with the postero-lateral angles of third pleon-segment sharply upturned. 



Telson cleft. 



The generic name Cheirimedon, xdp, the hand, and fjLeSwv, a lord, alludes to 

 the importance in this genus of the hand of the first gnathopods. As usual, when a 

 genus is founded for a single species, the characters sliould be regarded as preliminary 

 and liable to modification, should other closely related species be subsequently found 

 which could be included by small changes in the original definition of the genus, 



Cheirimedon crenatipcdmatus, n. sp. (PI. XII.). 



Head with a small rostrum and sharply produced lateral lobes ; first two segments of 

 the perseon short, third pleon-segment longer than any other of the segments, its postero- 

 lateral angles sharp, greatly upturned towards the downward bending dorsal margin, the 

 hind margin thus forming a deep cavity ; the fourth pleon-segment with a deej) dorsal 

 depression, the dorsal margin acutely prolonged backwards. 



Eyes not perceived, yet not certainly altogether absent. 



Upper AntennsB. — First joint long, cylindrical ; second and third short, narrowing 

 distally ; flagellum of twelve joints, of which the first is very long, equalling seven or 

 eight of the following joints combined, cylindrical, slightly tapering, w^ith only one or two 

 filamentary cylinders in our specimen, but an appearance as if a narrow brush of them 



