THE BAENACLES IN THE U. S. NATIONAL MUSEUM. 



35 



species. It sat upon a similar ribbed sea-urchin spine. It has the 

 capitulum 7.5 ram. long, 4. .5 wide; carina 6 mm. long-, 1.6 wide at 

 base. It agrees with Hoek's description and figures except that the 

 rostral latus is somewhat lower and the root" of the carina increases in 

 width more rapidly, being broader at the base than the type figure 

 shows. These differences among examples from one station are indic- 

 ative of a rtither wide range of individual variation. 



The species is related to S. portorlcanutii^ and more distantly to the 

 group of large forms of the S. velutinuiii type, from which it differs 

 chiefly by the shape of the cariiial latus. 



SCALPELLUM PORTORICANUM new species. 



1901. SndpellaiH {species) ? MigvajOvc , Bull. V. S. Fish Commission for 1900, II, 

 p. 179. 



Type.— Cii.t. No. 26358 U.S.N.M. 



Tiipe-locality. — Mayaguez Harbor, Porto Rico, between 25 and 76 

 fathoms, U. S. Fish Commission steamer Fish Haiok^ 1898-99. 



Fig. 8.— SCALPELLUM PORTORICANUM O, <■■, ROSTRAL AND CARINAL DETAILS; 6, LATERAL VIEW X 'H: <i, €, 

 S. PORTORICANUM INTONSUM. d,. DETAIL OF ROSTRUM; C, LATERAL VIEW •, A. 



The capitulum is rhombic-oblong, composed of 14 wholly calcified 

 plates, covered with a ver}^ thin and sparsely pilose cuticle. The 

 plates are weakly marked with lines of growth. The occludent margin 

 of the capitulum is nearly straight. 



The scutum is trapezoidal, more than twice as long as wide, occludent 

 and lateral margins parallel and straight, basal margin straight, nearly 

 at right angles to the occludent margin. Umbo apical, not projecting 

 beyond the occludent outline. 



The tergum is longer than the scutum and greater in area. Occlu- 

 dent margin straight; basal and carinal margins convex. The apex is 

 erect. 



The carina is not much curved, its umbo apical, against l)ut hardly 

 between the terga. The roof is flat, bounded by low lateral ribs, and 



