62 



BULLETIN 60, UNITED STATES NATIONAL MUSEUM. 



median latus. The inconspicuous umbo is at the upper fourth, in the 

 narrow portion of the plate. 



The rostrum is represented by a linear vestij^e almost concealed in 

 the cuticle. 



The rostral latera are subquadrate. The occludent and scutal mar- 

 gins are straight, nearl}^ equal, and at right angles. The basal mar- 

 gin is not much more than half as long as the scutal; and the lateral 

 margin is weakl}^ sigmoid. 



The inframedian latus is small, narrowly triangular, about half the 

 height of the rostral latera. The basal margin is scarcely half the 

 total length of the plate. Umbo at the obtuse ai)ex. 



The rostral latus is twice as high as wide, with four unequal sides, 

 no two of them parallel. The umbo is at the lower sixth of the 



straight car-inal margin, and hardh' pro- 

 jects beyond the carina. The carinal 

 margin is longest, basal and lateral short 

 and nearly equal. The upper angle is 

 acute. 



The peduncle is very short, with about 

 eight rows of eight transversely length- 

 ened, narrow scales each, the intervals 

 hairy. 



Length of capitulum 11, breadth 5.7 

 mm. Length of peduncle 4.5 mm. 

 Length of the carina 10, diameter at 

 base 1.1 mm. 



There is some uncertainty about the 

 number of plates, since the rostrum is 

 so inconspicuous that it may readil}^ be 

 overlooked. When so reduced as in this species it is likely to be absent 

 in some individuals. 



A single example was taken. The peculiar shape of the upper latus 

 and the very long carina, which passes between and entirely separates 

 the carinal latera, are its more conspicuous features. (Fig. 21.) 



SCALPELLUM SEMISCULPTUM, new species. 



Type.—Cs^t. No. 9888, U.S.N.M. 



Tyj)e-locality.— Albatross Station 2397, Gulf of Mexico, north lati- 

 tude 28° 42', west longitude 86° 36', in 280 fathoms, gray mud. 



The capitulum is about twice as long as wide, widest at the middle, 

 the occludent margin nearly or quite as much arched as the carinal; 

 composed of 13 fully calcified plates joined by linear sutures. The 

 cuticle is very thin and smooth. The plates are marked with lines of 

 growth and fine, inconspicuous radial striee, but the carinal latera have 

 distinct and strong radial riblets. 



a 



Fig. 24.— SCALPELLUM ANTILLARUM X 3, 

 WITH DETAILS OF 6, ROSTRUM AND C, 

 CAKINA. 



