by tiev. T. k. R. Stebbing. 21 



and //. dentatus, Kemp. From the latter it is decisively separated by 

 the fact that the fingers of the last three pcrseopods are not simple. 

 These fingers seem also to exclude H. vittatus, for in that species 

 Kemp says " On the last three legs there are five or six dactylar 

 spines which increase in size as they approach the apex (fig 8)." His 

 figure shows five teeth including the apex which reaches beyond the 

 large fourth spine. In our species there are only three to four "dactylar 

 spines 1 ' and the apex is very slight, not reaching beyond the preceding 

 strong jointed spine. 



The specimen figured was the largest available, being about an inch 

 in length, giving 9 mm. for the carapace and rostrum, and 16 mm. for 

 the pleon. The rostrum is slender, tapering, with six teeth above and 

 five of smaller dimensions below. At some distance to the rear is a 

 tooth on the carapace, such as suggested the specific name in Bate's 

 unirecedens. A rather smaller specimen, with carapace and rostrum 

 8 5 mm., and pleon 14 mm. long, has the apical part of the rostrum 

 upturned, eight teeth above and six below, with the receding tooth on 

 the carapace less remote than in the other specimen. This last detail 

 applies to a third specimen, in which, however, the rostrum is quite 

 straight and has nine teeth on its upper margin. 



The telson tapers to a blunt end from which a very small median 

 tooth or spine obtrudes, flanked by a single pair of divergent spines, 

 beneath which are planted five long plumose setse contrasting with the 

 seeming simplicity of the long setse fringing the telson's sides. 



In the second antennae the distal tooth is almost level with the 

 distal border. The mandibles and other mouth-organs do not seem to 

 differ materially from those of Exhippolysmdta. 



The fingers of the short and comparatively stout first peraeopods 

 close together completely or with a very narrow gap, and the wrist is 

 longer than the palm, instead of shorter as in //. marleyi, described 

 in these Annals in March, 1919. The wrist of the second perseopods 

 is composed of about twenty-one jointlets of which that nearest the hand 

 is the longest, the total being rather longer than the third and fourth 

 joints combined. The third joint is rather longer than the fourth and 

 in both subdivision, if present, is very obscure. The third peraeopod 

 is much stouter and somewhat longer than the second, having a fourth 

 joint subequal to the second's third and fourth combined. Its much 

 shorter fifth joint is distinguished by a protruding apex. The short 

 finger is as long as the hand of the second peraeopod. Its inner 

 margin carries three spines, of which the first is very small, but the 



