WEST AMERICAN PYRAMIDELLID MOLLUSKS. 159 



14 occur upon the second, 16 upon the third, and 18 upon the penul- 

 timate turn. Sutures well impressed. Periphery of the last whorl 

 marked by a slender channel. Base well rounded, marked by four 

 subeciual, broad, rounded keels, the spaces between which are marked 

 by slender riblets. Aperture subpjTiform; posterior angle obtuse; 

 outer lip thin, showing the external sculpture withm; columella 

 slender, strongly curved, decidedly reflected, provided with a weak 

 fold at its insertion. 



De Folin's type came from Margarita Island, Bay of Panama. 

 It has four and one-half post-nuclear whorls and measures: Length 

 2.2 mm., diameter 1 mm. 



ODOSTOMIA (CHRYSALLIDA) MONTEREYENSIS Dall and Bartsch. 



Plate 17, fig. (i. 



Odostomia (Chry sail Ida) montereyensis Dall and Bartsch, Proc. IT. S. Nat. Miis., 

 vol. 33, 1907, p. 51G, pi. 46, fig. 4. 



Shell broadly conic, milk-white to subdiaphanous. Nuclear whorls 

 smooth, largel}'^ immersed in the first of the succeeding turns, above 

 which only half of the last whorl projects. Post-nuclear whorls sepa- 

 rated b}^ broad, deep sutures ; well rounded between the sutures where 

 they are ornamented by four strongly tuberculate spiral ridges; the 

 spiral connections between the tubercles are equal to the axial con- 

 nections or ribs, of which 16 appear upon the second, 18 upon the thir- 

 tieth, and 20 upon the penultimate whorl. The spaces inclosed be- 

 tween the axial ribs and the spiral connections which join the rounded 

 tubercles are deep, squarish pits. The axial ribs extend strongly 

 across the deep peripheral channel and stop at the first subperipheral 

 keel. Base moderately long, well rounded, marked by five equal 

 and subequall}' spaced, well raised, strong, spiral keels, and a sixth, 

 much broader, low, and rounded at the columellar margin. The 

 grooves between the keels are equal to the width of the keels near 

 the periphery, but diminish in breadth successively from the periph- 

 ery to the umbilical area. They are crossed b}^ numerous slender, 

 raised, axial threads, which extend up on the sides of the spiral keels, 

 but do not cross them. There are about five of these threads between 

 each two ribs in the first subperipheral channel; aperture oval, some- 

 what effuse anteriorly; posterior angle acute; columella reenforced 

 by the attenuated base, against which it appears like a thickened 

 callus, provided with a moderately strong oblique fold at its inser- 

 tion; parietal wall covered by a thick callus, which joins the colu- 

 mella with the posterior angle of the aperture. 



The type (Cat. no. 196281, U.S.N.M.) has 5 post-nuclear whorls 

 and measures: Length 3 mm., diameter 1.3 mm. It was collected 

 by Mr. S. S. Berry, in 12 fathoms, off Del Monte, IMonterey Bay, 

 California. Three specimens from the same station are in ]\Ir. Berrj-'s 



