CRUSTACEA NORTH PACIFIC EXPLORING EXPEDITION 149 



setose; teeth as in the preceding species, but more minute and 

 sharper ; dactvH longer than in the preceding species and more slen- 

 der, those of the posterior pair of feet much more curved than the 

 rest. Dimensions of the carapax: Length. 0.19; breadth, 0.175 i"ch. 

 Found at Hongkong, China. 



LEUCOSIDEA 

 Genus LEUCOSIA (Fabricius) Leach 



The species of this genus which have recently become known are 

 very numerous, and although the distinctive marks are generally so 

 slight as to be determined with difficulty from descriptions or fig- 

 ures, they are nevertheless perfectly plain and satisfactory when 

 seen in the specimens themselves. The doubts thrown upon the 

 validity of some of the numerous species of Bell by certain German 

 authors are entirely unfounded; for several characters of a kind 

 which, in other genera of Brachyura, are merely indicative of variety 

 or individual peculiarities, here become of specific importance. 

 Color, for instance — usually and very properly disregarded as being 

 variable and of no specific value in most crabs- — is in the genus Lcn- 

 cosia a constant and important character. 



In Lcucosia the plane of the chelipeds is much more oblique to 

 the plane of the carapax than in most crabs, so that in their usual 

 position the anterior extremity is much elevated. They have usually 

 been delineated in this position, so that the post-brachial angle of the 

 inferior lateral margin cannot be seen. In our drawings we have 

 endeavored to represent the carapax in its own plane. 



In the larger pair of male abdominal appendages the spiral is .well 

 marked, and shows in the different species a number of turns vary- 

 ing from one and a half to eight or ten. 



245. LEUCOSIA VITTATA^ Stimpson 



Plate XVIII, Fig. 3, T,a 



Leucosia vittata Stimpson, Proc. Acad. Nat. Sci. Phila., x. p. 159 [57], 

 1858. 



Carapax rhomboidal, strongly convex ; breadth to length as 

 1:1.14. Surface punctate. Margins crenulated ; granules of an- 

 tero-lateral margins not conspicuous from above. Posterior mar- 

 gin straight, granulated, obtuse in the adult, rather projecting in the 



^ Lcucosidcs vittata (Stimpson). 



