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



the right mandible, as in the Lysianassiclse, is without an accessory plate. From 

 both of these groups it seems to be set far apart by the firm and definite structure 

 of the hand and nail in the second gnathopods, and by the general shallowness of the 

 body and side-plates. 



Valettia coheres, n. sp. (PI. XXXIV.). 



Rostrum rudimentary ; back round, but not broad ; postero-lateral angles of the 

 third pleon-segment acute, a little upturned ; fourth pleou -segment wdth a dorsal 

 depression, followed by a small distal hump ; sixth segment dorsally ridged on either 

 side of the telson. The commissures of the ganglionic chain stand distinctly apart ; the 

 ganglia have at each corner a globular packet of cells. 



Eyes not observed. 



Uliper Aiitennai. — Peduncle tumid, barrel-like, first joint scarcely longer than 

 broad, but much longer than the other two united, both of these being short, but broad ; 

 the flagellum of thirteen joints in one of the pair, of fourteen in the other ; the first 

 joint subequal in length to the peduncle, tapering, with a brush of cylinders in numerous 

 rows, the small joints that follow varying in length irregularly ; the secondary flagellum 

 slender, of four joints, which reach to the end of the second of the primary, tlie first of 

 the four equalling in length the other three united. 



Lower Antenna subequal in length to the upper ; first joint broad ; gland-cone of 

 the second joint prominent, acute ; third joint short, fourth joint as long as the preceding 

 three united, longer and stouter than the fifth, with setae along the upper edge and 

 a tuft at the lower distal angle ; the fifth joint about as long as the first three of 

 the fourteen joints of the flagellum, which, as in the upper antennae, vary in length 

 irregularly. 



U'p'per Lip. — Viewed laterally, two distal lobes are seen, one set with small prickles, 

 the other having a prominent tuft of cilia ; between the two lobes a curved margin 

 descends, which is also fringed with minute cilia. 



Mandibles short, with a broad shaft, cutting edge narrowly produced, not convex, 

 l^ut divided into five sharp teeth of unequal size ; secondary plate of the left mandible 

 elongate, projecting nearly as far as the cutting edge, similarly divided into teeth, the 

 longest tooth being slightly curved backwards ; spine-row of four short spines, of which 

 the first on the left mandible is bifurcate ; molar tubercle prominent, the crown more or 

 less dentate, with seven or eight spine-like cilia at the back and a long plumose seta ; 

 the palp set well forward, just over the molar tubercle, the first joint short, the second 

 stout, very little longer than the third, with twelve spines on the upper part of the 

 inner margin, the third joint distally pointed, with twelve spines on the upper part of 

 the inner margin, most of them smaller than those of the second joint. I can find no 



