NO. 1863. MOLLUSKS OF THE GENUS ALVANIA—BARTSCII. 353 



nuclear whorls appressed at the summit, strongly, slopingly shouldered, 

 the shoulder extending from the summit to the anterior termination 

 of the posterior third between the sutures, marked by two strong 

 nodulose, spiral keels, of which the first is situated on the angle of 

 the shoulder, while the second is about as far posterior to the suture 

 as the first is anterior to the summit. In addition to these spiral 

 keels, the whorls are marked by moderately strong, axial ribs which 

 become enfeebled on the shoulder and anterior to the second keel. 

 Of these ribs, 16 occur upon the first and second, and 18 upon the 

 penultimate turn. The spaces mclosed between the spiral keels and 

 axial ribs are large, deeply impressed, squarish pits, while their junc- 

 tions form cusplike tubercles. Suture strongly channeled. Periph- 

 ery of the last whorl marked by a strong, sublamellar, spiral keel. 

 Base moderately long, marked by three spiral keels, which grow suc- 

 cessively weaker and closer "spaced from the periphery to the umbili- 

 cal area. The broad spaces between the spiral keels are marked by 

 slender, axial lines of growth. Aperture broadly ovate; posterior 

 angle obtuse ; outer lip reenf orced immediately behind the edge by a 

 strong varix, transparent, showing the external sculpture within; 

 inner lip rather stout, decidedly curved, and strongly reflected over 

 and appressed to the base; parietal wall covered with a thick callus 

 which renders the peritreme complete. 



The type (Cat. No. 213698, U.S.N.M.) comes from San- Pedro, Cali- 

 fornia. It has 3^ post-nuclear whorls and measures: Length 2.2 

 mm., diameter 1.2 mm. Cat. No. 162661, U.S.N.M., contams one 

 specimen from La Jolla, California, and Cat. No. 162664, U.S.N.M., 

 contains one from San Martin Island, Lower California. 



ALVANIA PURPUREA Dall. 

 Plate 31, fig. 1. 

 Alvania purpurea Dall, Amer. Journ. Conch., vol. 7, 1872, pp. 116-17. 



Shell elongate-ovate, light yellow. Nuclear whorls one and one- 

 half, well rounded, ver}'' finely papillose. Post-nuclear whorls 

 appressed at the summit, strongly, slopingly shouldered, marked by 

 lamellar, slightly retractive, axial ribs, of which 18 occur upon the 

 first and second, and 20 upon the penultimate turn. In addition to 

 these axial ribs, the whorls are marked between the sutures by two 

 spiral lamellae which divide the space between the sutures into two 

 almost equal portions, the one at the summit being a little narrower 

 than the other. The junctions of the axial and spiral sculpture form 

 spiral cusps, while the spaces inclosed between them are broadly rec- 

 tangular pits, having their long axes parallel with the axial sculpture. 

 The spaces inclosed between the summit, the first spiral lamella, and 

 the axial ribs are rhomboidal, while those between the second spiral 

 lamella, the suture, and the axial ribs are very broadly rhomboidal. 

 94428°— Proc.N.M.vol.41— 11 23 



