122 



BULLETIN 



UNITED STATES NATIONAL MUSEUM. 



TURBONttLA (DUNKERIA) LAMINATA Carpenter. 

 Plate 12, figs. 16, IGa. 

 Dunhria laminata Carpenter, Ann. Mag. Nat. Hist., 3d ser., vol. 15, 1865, p. 396. 



Shell broadly conic, wax yellow at the tip, chestnut-brown on the 

 last whorl, columellar area white. Nuclear whorls two and one-half, 

 forming a depressed helicoid spire, whose axis is at right angles to 

 that of the succeeding turns, in the first of which it is about one- 

 fourth immersed. Post-nuclear whorls inflated, strongly rounded, 

 moderately contracted at the suture, marked by very regular, 

 rounded, strong, almost vertical axial ribs, of which 18 occur upon the 

 first, 24 upon the second, 26 upon the tliird, 28 upon the fourth and 

 fifth, 30 upon the sixth and seventh, and about 40 upon the penulti- 

 mate turn. Intercostal spaces a little wider than the ribs, crossed by 

 five spiral series of broad, deep pits, which cause the five intermediate 

 areas to appear as broad, raised bands, wliich are about as wide as 

 the ribs, and render their junction with the ribs tuberculate. Sutures 

 strongly impressed. Periphery of the last whorl well rounded. Base 

 moderately long, marked by the faint continuations of the axial ribs, 

 and about ten spiral lirations, which are narrower and less strongly 

 developed about the umbilical area. Aperture broadly oval ; posterior 

 angle acute; outer lip thin, showing the external markings ^\dthin; 

 columella strongly curved, and completely reenforced by the base. 



The specimen described and figured (Cat. no. 9465, U.S.N.M.) was 

 collected by Cooper at San Pedro, California. It has nine post- 

 nuclear whorls and measures: Length 6.6 mm., diameter 2.1 mm. 



The coloration of this species varies considerably; it may be uni- 

 color, wliite to chestnut, or diversely banded. 



