86 BULLETIN 111, UNITED STATES NATIONAL MUSEUM. 



Subgenus FUSTIARIA Stoliczka, 1868. 



1868. Fustiaria Stoliczka, Mem. Geol. Survey of India, Cretaceous Fauna of 

 Southern India, vol. 2, p. 439. 



Shell either polished smooth and sculptureless or with encircling 

 grooves, having a round section. The apical orifice is round or ovate 

 and has a very long, straight linear cleft on the convex side. 



The subgenus includes but few recent forms, and but one species 

 in the faunal areas here considered. The important feature of the 

 subgenus is the very long apical cleft. It represents the extreme of 

 the apical characters referred to as an "apical slit." 



DENTALIUM (FUSTIARIA) STENOSCHIZUM Pilsbry and Sharp. 



Plate 15, figs. 8, 9. 



i860. Dentalium translucidiim Sowerby, Tlies. Conch., vol. 3, p. 98, pi. 225, fig. 47 



(not of Deshayes, 1821). 

 1872. Dentalium translucidem Sowerby, Reeve's Conch. Icon., vol. 13, pi. 6, 



fig. 39. 

 1897. Dentalium (Fustiaria) stenoschizam Pilsbry and Sharp, Tryon'e Man. 



Conch., vol. 17, p. 129, pi. 19, figs. 10-15. 

 1901. Dentalium (Fustiaria) stenoschizum, Dall and Simpson, Bull. U. S. Fish 



Conim. for 1900, vol. 1, p. 457. 



The shell is rather strongly curved, having the maximum curvature 

 in the posterior portion; it is regularly and rapidly increasing in 

 diameter. The section is round; the shell is thin throughout, and 

 almost fragile at the oral aperture. It is white, with a polished, 

 smooth shining surface, transparent at the aperture and translucent 

 elsewhere, and is wholly sculptureless. It possesses an extremely 

 long and narrow apical slit, which in some specimens is quite one- 

 fourth the entire length of the shell. This long cleft is on the convex 

 side. Measurements are: 



Length, 35 mm.; diameter, 3.4 mm. (Pilsbry). 



Length, 26 mm.; diameter, 2.75 mm.; arc, 1.75 (Porto Rico). 



This is the only species of this group so far recorded from the west- 

 ern Atlantic. 



The museum lots are: One specimen. Cat. No. 161577, U.S.N.M., 

 from Mayaguez Harbor, Porto Rico, U. S. B. F.; one specimen. Cat. 

 No. 314837, U.S.N.M., collected by the State University of Iowa 

 Expedition at their station 88, off the Lazaretto, Barbados, in about 

 100 fathoms; two specimens, Cat. No. 314838, U.S.N.M., collected 

 by the State University of Iowa Expedition at their station 10, in 100 

 fathoms, off Pelican Island, Barbados; one specimen, Cat. No. 

 314907, U.S.N.M., dredged at Eolis Station 317, off the Western Dry 

 Rocks, Florida, in 1 10 fathoms. 



