WEST AMERICAN PYRAMIDELLID MOLLUSKS. 115 



whorls is traversed by five spiral grooves, which appear most promi- 

 nently in the shallow and broad intercostal spaces, and less so on the 

 ribs; these deep spiral lines are regularly spaced, leaving a broader 

 interval on the middle of the exposed portion of the whorl; the base 

 of the last whorl is likewise ornamented by spiral grooves, but here 

 they appear less developed than on the spire. In addition to this the 

 entire surface of the shell is marked by numerous very fine, somewhat 

 wav}^, spiral and axial striae, which show most prominently on the last 

 whorl and base, and give the shell a very minutely reticulated second- 

 ary sculpture. At irregular intervals the whorls are marked by thick 

 callous varices, which are usually of a lighter color than the remainder 

 of the shell. Aperture large, subquadrate; posterior angle acute; 

 outer lip thin, having three strong internal lirations, joining the 

 whitish, short, straight, revolute columella at a little less than a 

 right angle. By transmitted light two spiral light color-bands be- 

 come apparent on the inside of the lip, each of which is bordered by 

 a zone of a darker color than the remaining shell. The general color 

 effect of the exterior is that of a flesh-colored shell, covered by a 

 dark epidermis, which is stretched tight over the ribs, permitting 

 the lighter color beneath to shine through it at their summits. 



Doctor Carpenter's type (Cat. no. 153156, U.S.N.M.) was collected 

 at Monterey, California. It has 1 1 post-nuclear whorls and measures: 

 Length 11.1 mm., diameter 3.2 mm. The specimen figured (Cat. no. 

 150983, U.S.N.M.) is from San Pedro, California. It has 13 post- 

 nuclear whorls and measures: Length 12.8 mm., diameter 3.6 mm. 



The U. S. National Museum has five lots of this species: Cat. no. 

 153156 is the t3^pe from Monterey, California; Cat. no. 196239, four 

 specimens dredged by the Bureau of Fisheries steamer Albatross at 

 station 2902, off Santa Rosa Island, in 53 fathoms, fine gray sand 

 and mud, with a bottom temperature of 45°; Cat. no. 196240, ten 

 specimens from San Pedro, collected by Mrs. T. S. Oldroyd; Cat. no. 

 150983, three individuals, one of which is figured, dredged by Mrs. 

 Oldroyd in 4 fathoms, at San Pedro; Cat. no. 46505, two shells from 

 San Diego in the Stearns collection. In addition to these, specimens 

 have been determined for Mr. Berry, from Monterey, 12 to 39 fathoms; 

 Um'versity of California, off Catalina Island; Mrs. Oldroyd and Mr. 

 Lowe, at San Pedro; Mr. Kelsey and Mr. Arnold, from San Diego. 



TURBONILLA (MORMULA) AMBUSTA, new species. 



Plate 11, fig. I'i. 



Shell medium size, slender, chestnut-brown. (Nuclear whorls de- 

 collated.) Post-nuclear whorls moderately rounded, appressed at the 

 summit, slightly contracted at the periphery, marked by strong, 

 rounded, slightly protractive axial ribs, of which 16 occur upon the 



