112 Mr. W. Thompson on neio species of British Crustacea. 



{vAr. falcatus) : should I obtain evidence of their being distinct 

 species, the specific names will then be probably changed. 



I now find that some few specimens of H. Whitei are of a 

 brownish colour; these had been brought home in a brass box. 



HiPPOLYTE Yarrellii (mihi). YarrelVs Hippolyte. 

 PI. VI. fig. 2. 



Spec. Char. Rostrum (fig. 2 a) shorty bent downwards, in- 

 curved at the base, hollowed out above, with four spinous teeth 

 above. The apex tridentate, the upper tooth the longest, the 

 middle tooth longer than the lower one. 



The carapace is short and rounded ; the rostrum short, bent 

 downwards, and suddenly widening near the apex, armed above 

 with four spinous teeth bent forwards at an acute angle; the 

 first, which is not very prominent, is placed on the carapace at 

 the base of the carina, which forms the continuation of the 

 rostrum ; the second immediately in a line with the ocular notch ; 

 the third, which is the longest, is placed in a line over the middle 

 of the peduncle of the eye when the eye is directed forward ; 

 and the fourth is placed on the rostrum, and about twice its 

 own length from the apex. The upper edge of the rostrum is 

 much hollowed out ; the lower edge of the rostrum is straight, 

 with an inclination downwards, unarmed, and ending in an acute 

 angle. The apex is deep and tridentate; it is formed of the 

 tooth just described, and two others projecting beyond it. The 

 upper tooth is longer than the second and slightly inflected ; the 

 second is very acute, and longer than the bottom, which appears 

 to be formed by a portion being scooped out. The two upper 

 teeth bend upwards, whilst the bottom bends slightly down- 

 wards ; this widens the apex. 



The scale of the external antennse extends to more than half 

 the length of the filaments of the internal antennse. Marginal 

 tooth terminal, not so long as in H. Cranchii. Anterior feet 

 extending forwards a little beyond the antennal scale; second 

 pair with the wrist long. The junction of the abdomen and 

 thorax very gibbous. 



The process on the posterior margin of the third segment 

 much more prominent, and running more to a point than in H. 

 Cranchii. 



The middle portion of the tail has five or six pairs of spines 

 placed on it, and not on the margin. 



Length about f of an inch ; colour brown, blotched with a 

 darker or claret-colour. 



I obtained two individuals whilst dredging in Weymouth Bay 

 on the 18th of August 1852, in from five to seven fathom water, 

 on a bed of Rytiphlcea pinastroides. One carried ova, which were 



