76 Mr. R. I. Pocock on 



15. Hyastemis (Chorilia) tenuicornis, sp. n. 



Carapace pyriform, with well-defined regions ; the rostral 

 spines hairy, exceedingly long and diverging, i. e. each spine 

 is considerably longer than the carapace and the distance be- 

 tween their apices is about equal to their length ; the super- 

 numerary rostral tooth, which is said to be characteristic of 

 the genus Naxia, is absent ; the antennal and orbital spine3 

 are very strong ; from the base of each there runs backwards 

 towards the margin of the posterior half of the orbit a tooth 

 which in the case of the orbital spine partially bridges over 

 the upper orbital hiatus ; the orbital hiatus very large and 

 the posterior portion of the orbit in consequence small and 

 pillar-shaped ; from its upper surface it sends forward a pro- 

 jection in the direction of, but not reaching, the backwardly 

 prolonged tooth from the upper orbital spine ; these two pro- 

 jections almost fill up the aperture of the upper orbital 

 hiatus ; the superior interorbital area furnished with two sub- 

 parallel longitudinal series of tubercles; the gastric region of 

 the carapace furnished with larger and smaller, not close-set 

 tubercles, of which three in the middle line and one on each 

 side are the largest ; the cardiac region armed with two 

 enormous tooth-like tubercles set in longitudinal series ; the 

 branchial region armed with three large teeth, of which the 

 hindmost is the largest. 



Chelipedes long, projecting slightly beyond the apex of the 

 rostral spines ; merus cylindrical, furnished at its distal end 

 with a spine above and an articular tubercle on each side ; 

 manus long and slender, with an articular tubercle above 

 and below at its proximal end and a longitudinally grooved 

 external surface. 



Legs almost alike, differing principally in length and in 

 the fact that the merus of the first pair is furnished at its 

 distal end with an enormous spine, which is scarcely repre- 

 sented on the other legs. 



Measurements in millimetres. — Length of carapace 10, 

 width 7, width outside orbits 4| ; length of rostral spine 12£ ; 

 distance between apices of spines 12^ ; length of chelipede 

 17£, of first leg 27|, of last 13. 



The colour (in spirit) of this specimen is very beautiful ; 

 the bases of the legs and of the rostral spines, the interorbital 

 area, and the an tero- lateral portions of the carapace are car- 

 mine, the upper portions of the branchial region are bluish 

 grey, the rest yellowish white. 



One specimen at a depth of 32 fath., another at a depth of 

 25 fath., on Macclesfield Bank. 



