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BULLETIN fiO, UNITED STATES NATIONAL MUSEUM. 



vitreuni Hoek of the Pacilic, aS'. curvatum Gruvel, f(il!siii((nl (ji'uvel, 

 and S. rigidnm Anrivillius of the northeast Atlantic (Azores to the 

 Gulf of Gasc'ony). S. formosum stands niMirest ,5'. talismani, but 

 differs by the longer inframedian lateral plate (which in taJiwKin! is 

 in form of an isoceles triangle), the lower rostral latera, and the 

 somewhat different sculpture of the carinal latera. 



From Station 2205 only the detached valves of a macerated specimen 

 are preserved. It is larger than the type, the carina measuring 18.5 

 mm. long, 3.3 wide. The sculpture is very sharp and })eautiful. The 

 dorsal faces of the carinal latera are radially tricostate. (Fig. 22.) 



SCALPELLUM GRACILE, new species. 



Type.-C^t. No. 32908 U.S.N.M. 



Typp-locality. — Alhatross; Station 2791, off* Chile, south latitude 



38° 08', west longitude 75° 53', 

 in (577 fathoms; ])ottom tem- 

 perature, 37.9° F. 



The capitulum is slenderh^ 

 oval, widest in the middle, the 

 ventral and dorsal ])orders 

 equally curved, base narrow. 

 It is composed of 14 wholly cal- 

 citied plates, the upper lateral 

 plates and carina separated b}'^ 

 chitinons spaces from the oth- 

 ers. Cuticle very thin and 

 smooth. Most of the plates 

 show very faint radial striation. 

 The scutum is wider at and 

 above the middle than toward 

 the base. The occludent margin is straight except near the apex, 

 where it curves inward. The lateral margin is somewhat convex. 

 The umbo is at the acuminate apex, which overlies the adjacent angle 

 of the tergum. 



Tergum longer than the scutum, triangular, the occludent and basal 

 margins about equal in length, the former convex, the latter straight. 

 The carinal margin is straight. Apex erect. 



The carina is long and evenly arched, with apical umbo. The roof 

 is convex, between two high lateral ribs. The sides are narrow, but 

 widest near the apex. 



The upper lateral plate is about as wide as the scuta, quadrangular, 

 with the scutal and. carinal borders parallel, the carinal about half 

 as long as the scutal; basal and tergal margins are straight and about 

 equal in length. The umbo is acute and apical. 



The rostrum is very narrow and long, a trifle wider tow^ard the base. 

 It separates the rostral latera throughout. 



Fir.. 23.— SCALPELLUM GRACILE X 4, WITH h, DETAILS 

 OF ROSTRUM, AND C, CARINA. 



