CRUSTACEA NORTH PACIFIC EXPLORING EXPEDITION 163 



SO that the upper surface is concave on either side of the dorsal 

 convexity, which is ahnost carinate along the middle. The front is 

 rostrate ; the rostrum broad and triangular, pointing obliquely up- 

 ward. Orbits minute, round, with entire margins. Antennulary 

 fossse oblique. External antenna nearly obsolete, or represented 

 only by one or two joints at the base. Epistome sufficiently large. 

 Buccal area as broad as long. Anterior margins of the ptervgos- 

 tomian channel entire. Exognath of the outer maxillipeds dilated, 

 as broad as the endognath, its outer margin broadly and regularly 

 arcuated. Meros-joint of the endognath two-thirds as long as the 

 ischium. Chelipeds with laminiform crests at the edges ; fingers of 

 the hand short. Dactyli of the ambulatory feet very narrow. Ster- 

 num broad. Abdomen of the male narrow-triangular, geniculated 

 near the base ( where, however, there is no joint) in a right angle, 

 its segments all confluent with the exception of the first and last. 



This little crab has much resemblance to a Cryptopodia. and in its 

 natural position the main body of the carapax anteriorly is directed 

 obliquely upward and forward at an angle of 45°. 



263. CRYPTOCNEMUS PENTAGONUS Stimpson 



Plate XIV, Fig. 5,6 



Cryftociicinus poitagonus Stimpson, Proc. Acad. Nat. Sci. Phila., x, p. 

 ' 162 [60], 1858. 



Carapax much broader than long in the proportion of i : 1.45. 

 The length of the postero-lateral side is one-half that of the antero- 

 lateral. The surface is perfectly smooth and glabrous, and convex 

 anteriorly, with a slight longitudinal ridge or carina running from 

 the tip of the rostrum to the middle of the gastric region. The 

 small cardiac region is slightly prominent. The rostrum is ele- 

 vated to an angle of about 60° with the horizon ; tip almost acute ; 

 sides convex. The outer maxillipeds and all the lower surfaces of 

 the body are smooth and glossy. The chelipeds are flattened, with 

 glabrous surfaces ; the marginal laminae very much expanded, that 

 of the hand being wider than the slight thickening which constitutes 

 its body, and deeply notched on the outer side near the fingers. The 

 fingers are one-third as long as the palm ; immovable finger broad ; 

 dactylus sulcated. Ambulatory feet crested with laminae; dactyli 

 very slender. Color of preserved specimen white. Dimensions of 

 the carapax in the male : Length, 0.2 ; breadth, 0.29 inch. 



Dredged from shelly mud in twenty fathoms, in Kagosima Bay, 

 Japan. 



