MUSEUM OF COMPARATIVE ZOOLOGY. 115 



family with the latter group, for which the name Naxiinae is here proposed. 

 The deep notch on the upper side of the orbit is here a constant char- 

 acter. 



Scyra umbonata nov. sp. 



Carapax triangular, with six large flat-topped protuberances on the 

 Upper surface ; one on the posterior part of the gastric region, one on the 

 cardiac, and two on each branchial region. On the outer side of the 

 branchial region there is also an acute triangular tooth, pointing forward 

 and outward, and of similar character and nearly as large as the other 

 protuberances just described. They are all not only flattened, but some- 

 what expanded at the top. Their summits are naked, but the deep chan- 

 nels between them are pubescent. Besides the above there are on the 

 carapax three small tubercles on the gastric and a strong erect tooth on 

 each hepatic region. The gastric and the sides of the branchial regions 

 are hairy. The rostrum is rather longer than the interorbital width of 

 the carapax ; it is hairy above, and is neither flattened nor expanded. The 

 movable part of the external antenna? has cylindrical joints. The meros- 

 joint of the external maxillipeds is not notched for the reception of the 

 palpus. Abdomen and sternum pubescent. Sternum of the male with 

 deep excavations between the segments, the excavations being broader 

 than the ridges separating them. 



Dimensions of a male : Length of carapax, 0.94 ; breadth, measured 

 between the tips of the branchial teeth, 0.72 inch. 



The species of Scyra heretofore known are but two in number, and in- 

 habit waters of moderate depth on the shores of the North Pacific Ocean, 

 one on the coast of California and Oregon, the other on that of Japan. The 

 present species was placed in the genus with some doubt, on account of 

 the character of the rostrum, the external antenna?, and the outer maxilli- 

 peds, whudi, as may be noticed by the description, differ somewhat from 

 those of the type, S. acutifrons. The resemblance in all other essential 

 characters is, however, very great ; and in the present state of our knowl- 

 edge, the Florida species ought not to be separated as the type of a distinct 

 genus. 



It is an inhabitant of deep water, as follows : — 



Off Sand Key, May 11, 1868. Cast No. 15. 143 fathoms. 



Subfamily OTHONIINAE. 



The Othoniinae are characterized by great orbito-frontal breadth, a 

 small, short rostrum, an extremely short epistome, and gaping external 

 maxillipeds. The orbits are tubular like those of the Pericerinae, but are 

 directed forwards instead of outwards. 



