398 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 40. 



Specimens examined. 



•Type. 

 BITTIUM (SEMIBITTIUM) QUADRIFILATUM Carpenter. 



Plate 58, figB. 2 and 3. 



Bittium quadrifilatum Carpenter, Rep. Brit. Ass. Adv. Sci. for 1863, 1864, p. 655. 

 Bittium quadrifilatum Carpenter, Journ. Conch., ser. 3, vol. 5, 1865, p. 143. 



Shell rather large, elongate-conic, chestnut brown, dull. Nuclear 

 whorls two, well rounded, smooth, the first obliquely tilted. Post- 

 nuclear whorls shouldered at the summit, moderately rounded, 

 ornamented with four equal and subequally spaced spiral cords, which 

 divide the space between the sutures into four subequal parts. The 

 first of these cords is at the summit of the whorl. In addition to the 

 spiral cords, the whorls are marked by moderately strong, rounded, 

 vertical, axial ribs, of which 12 occur upon the first, 14 upon the second 

 to fifth, 16 upon the sixth, 18 upon the seventh and the penultimate 

 turn. The spiral cords cross the axial ribs as regular bands, their 

 junctions forming elongated rounded tubercles, having their long 

 axes parallel with the spiral sculpture, while the spaces inclosed 

 between them are well impressed quadrangular pits with their long 

 axes also parallel with the spiral sculpture. On the last whorl very 

 faint, intercalated spiral threads appear between the cords. Sutures 

 channeled, showing a faint trace of the subperipheral cord. Periphery 

 of the last whorl marked by a rather broad channel which shows 

 several faint spiral lirations. Base moderately long, somewhat 

 concave, ornamented with seven subequal and subequally spaced, 

 spiral threads. Aperture irregularly oval, channeled anteriorly; 

 posterior angle obtuse; outer lip thin, showing the external sculpture 

 within; columella moderately long, somewhat twisted, and reflected. 



The specimen described and figured is one of a lot (Cat. No. 46929, 

 U.S.N. M.) from San Diego, California. It has the nucleus and nine 

 post-nuclear whorls and measures: Length 11.5 mm., diameter 3.6 mm. 

 Doctor Carpenter's type of this species (Cat. No. 14849, U.S.N.M.) 

 which was collected by Doctor Cooper at San Diego, California, is a 

 young specimen having seven post-nuclear whorls, measuring: 

 Length 7 mm., diameter 3 mm. The fossil members of this species 



