CRUSTACEA NORTH PACIFIC EXPLORING EXPEDITION I47 



of the carapax anteriorly and laterally project very considerably in 

 a horizontal direction, concealing the eyes, antennas, and bases of the 

 feet. They project most anteriorly in the adult female. Front 

 sufficiently prominent, broadly truncated ; interantennulary septum 

 strongly projecting. Antennulse small. The inferior surface, 

 against which the eyes rest, is considerably hollowed out for their 

 reception. Buccal area small in the female. Outer maxillipeds 

 nearly as in T. unguiformis. Chelipeds of the male long, smoothly 

 rounded ; meros slender ; hand oblong, inflated ; fingers somewhat 

 excavated within throughout their length. Ambulatory feet slender, 

 smooth, naked, a small spine at the superior extremity of the meros 

 and carpus-joints ; dactyli greatly compressed, strongly falciform, 

 not tapering, but of equal breadth even to their tips. Abdomen of 

 the male somewhat elongated, triangular, its extremity reaching 

 nearer to the mouth than is the case in T. unguiformis. 



Color in life dark purplish-red above, with four white spots on 

 the carapax — two at the bases of the posterior pair of feet, and two 

 smaller ones in front of them. Dimensions of a male : Length of 

 carapax, 0.21: breadth, 0.225; length of cheliped, 0.4; of ambula- 

 tory foot of second pair, 0.56. In the female: Length of carapax, 

 0.298 ; breadth, 0.362 inch. 



Found under stones at low-water mark, in weedy rock pools. 

 Also dredged in eight fathoms, sandy bottom. It occurred at 

 Ousima and among the reefs opposite Napa, Loo Choo. 



Genus RHYXCHOPLAX Stimpson 



This genus resembles Trigonoplax in form. The body is trian- 

 gular, but less depressed, and longer than broad. Lateral margin 

 bidentate. . Rostrum arising from beneath the anterior margin of 

 the dorsum, tridentate, the median tooth largest, elongated, bent up- 

 ward ; the lateral teeth minute and sharp. Antennulce rather large, 

 approximated, not separated by a septum. Eyes not retractile. 

 Extraorbital spine small. Subhepatic region prominent, with some- 

 what acute summit. Epistome large. Ischium-joint of the external 

 maxillipeds scarcely larger than the meros. Chelipeds of the male 

 large and strong, scarcely shorter than the walking feet. .Ambula- 

 tory feet of the first pair longest; dactyli of all falciform, much 

 curved. Abdomen of the male oblong and lightly contracted toward 

 the extremity. 



This genus ap[)roaches still nearer to the Maioids than Trigono- 

 plax, but, like that, is excluded from that division by its sternal 

 verges. 



