CRUSTACEA NORTH PACIFIC EXPLORING EXPEDITION 65 



over it. Tlie deep median emargination of the front is at the termi- 

 nation of a longitndinal groove on the anterior surface of the cara- 

 pax, and close on each side of it the margin projects into a small 

 rounded tooth or lobe. Margins of orbit nearly smooth, the external 

 hiatus being nearl\- obsolete. Hectognathopoda smooth ; their inner 

 margins not in contact, but separated by a sufficiently conspicuous 

 subrhomboidal space in which lie the palpi. Subhepatic and sub- 

 branchial regions smooth. Chelopoda large, resembling those of 

 Eucratc : meros with a tooth near the summit; carpus smooth, with 

 a small tooth at its inner angle ; hands smooth, fingers slender, de- 

 flexed, white. Ambulatory feet slender, somewhat hairy, those of 

 the second pair longest. Abdomen and posterior half of sternum 

 minutely pubescent. The abdomen is narrow and tapering. 



Dimensions: Length of carapax, 0.32; breadth, 0.4 inch. 



The carapax in this species is narrower than in any other form of 

 Xanthidre. The form, the shortness of the antero-lateral margin, 

 the form of the hands, and some other characters may perhaps indi- 

 cate a genus distinct from that to which it is here referred. The 

 general appearance is much like that of some forms of Gonoplacidc-e 

 and Carcinoplacidse, but the position of the male verges is the same 

 as in the Cancroids. 



Found at Hongkong. 



Genus PTLUMXUS Leach 



The numerous species referred to this genus, more than thirty of 

 which have been now described, will probably be found upon critical 

 examination to afford characters which will require its separation 

 into several groups. Some of those described below are placed here 

 with much hesitation, although agreeing with the received diagnosis 

 of the genus. 



The basal joint of the external antennae is somewhat mobile in all 

 the species which we have examined. 



89. PILUMNUS VESPERTILIO (Fabricius) Leach 



Cancer vcspcrtilio Fabricius. 



PUitmnus I'cspcrtUio Leach, Trans. Lin. Soc, xi; LatreillE, Encyc, .\, 



125; MiLNK Edwards, Hist. Nat. des Crust., i, 418, 

 Pilumnus iitus Dana, Lf. S. Exploring Expedition. Crust., i. 240: Stimp- 



sox, Proc. Acad. Nat. Sci. Phila.. x, p. 36 [33], 1858. 



This species is thickly covered with long dirty-greyish hair. The 

 naked parts beneath are white ; fingers dark brown ; eyes black. 



