1404 THE VOYAGE OF H.M.S. CHALLENGEK. 



Upper Lip unsymmetrically bilobed, apparently with the surface very minutely 

 furred near the small distal emargination. 



Mandibles with a rather short trunk, the cutting edge small, divided into ten little 

 teeth ; the secondary plate of the left mandible (figured on the right hand of the Plate) 

 much narrower than the principal, and apparently with fewer teeth ; the molar tubercle 

 broad and prominent, having on one edge of the crown a series of about twenty-one little 

 spine-like teeth standing apart from one another, on the other edge a row of broad 

 denticles, and several rows of minute denticles on the face of the crown ; the palp is 

 narrow, longer than the trunk, the first joint more than half the length of the second, 

 which curves a little outwards, the third tapering, rather longer than the second. 



Lower Lip. — The forward lobes not broad, wide apart, the rounded distal margins 

 strongly ciliated ; the mandibular processes rounded, divergent. 



First Maxillse. — Outer plate short and broad, distally folded, beset with strong 

 bristles, and distally carrying five stout spines, two of which are of rather conspicuous 

 size ; the palp broad, reaching beyond the outer plate, having a longitudinal fold or 

 ridge rising from the base, the inner margin closely fringed with spinules till within a 

 little of the toothed apex, just within which the distal margin has a stout little double 

 pointed spine-tooth, beyond this being cut into about a dozen little denticles ; several 

 little spines or prickles are set on the surface, a little below the distal margin. 



Second Maxillse. — The outer plate longer than the joint on which it stands, apically 

 pointed but not acutely, thickly set with bristles and spines, the two of the latter at the 

 apex being tolerably strong ; the inner plate much shorter, not very dissimilar. 



Maxillipeds short ; the inner plate very inconspicuous when the maxillipeds are 

 viewed from the outer surface ; the principal joint has on this outer surface just within 

 the distal margin a fan-like arrangement of five large spines, the distal half of each 

 finely feathered, the central spine the longest ; the outer plates are not much shorter 

 than the joint on which they stand, the inner margin almost smooth for more than half 

 its length from the base, then serrate and fringed with a number of little spinules of 

 different sizes ; the apex has a spinule and there are two or three minute ones on the 

 outer margin just below the apex. 



First Gnathopods. — Side-plates deeper than broad, the upper boundary pretty dis- 

 tinctly marked in this and the following pairs. The first joint about as long as the 

 third, fourth, and fifth joints together, of nearly uniform breadth throughout, channelled 

 along the lower three-fourths of the front margin ; there are two spines at the apex of the 

 hind margin ; the second joint not longer than broad, with three spines at the hinder 

 apex ; the third joint widening distally and a little produced, projecting behind the 

 wrist, the produced apical border beset with several strong spines, the hind margin 

 smooth except for a little pectination at the apex ; the wrist widening distally so as to be 

 there much broader than the hand, the front margin smooth, with two apical spines, the 



