ARNOLD — THE PALEONTOLOGY AND STKATIGEAPHY OF SAN PEDBO. 283 



[S. D.] Odostomia (Amaura) pupiformis Carpenter. 



Plate I, Fig. 13. 



Odostomia satura \zx. pupiformis Cpr., Ann. Mag. Nat. Hist., 3rd Ser., Vol. XV, 1865, p. 30. 



Shell broadly conic, umbilicated, rather thin, white, shining, of rather rough exterior; 

 nuclear whorls immersed; post-nuclear whorls somewhat rounded and shouldered at the summit; 

 suture deep and channeled; base and periphery of the last whorl decidedly rounded; aperture large, 

 broadly ovate; posterior angle acute; outer lip somewhat effuse in its anterior margin; columella 

 thin and flexuose, provided with a prominent oblique fold a little anterior to the umbilicus; a weak 

 callus covers the parietal wall. 



Dimensions. — Long. 6.4 mm.; diam. 3.3 mm. 



The type was collected at Neeah Bay, Washington, and has six post-nuclear 

 whorls. The strong umbilication and the light weight of the shell enable one to 

 distinguish it quite readily from all the other forms of this section. The species 

 ranges recent from Alaska to San Diego. Fossil specimens have been found in the 

 post-Pliocene beds of San Diego. 



304. Odostomia (Amaura) nuciformis, var. avellana Carpenter. 



Plate I, Fig. 11. 



Odostomia ( ? var.) avellana Cpr., Ann. Mag. Nat. Hist., 3rd Ser., Vol. XV, 1865, p. 30. 



Shell large, stout and inflated, white; nuclear whorls small, immersed; post-nuclear whorls 

 somewhat rounded, rather broad, marked only by thin lines of growth; sutures quite prominent, sub- 

 channeled; base and periphery of the last whorl well rounded; aperture large, subovate; posterior 

 angle obtuse; outer lip somewhat contracted, while the anterior margin is somewhat efTuse; columella 

 short and flexuose, provided with a strong, broad fold just anterior to the umbilical chink; a strong 

 callus extends from the posterior angle of the aperture to the base of the columella and renders the 

 peritreme almost continuous. 



Dimensiojis. — Long. 9.1 mm.; diam. 4.4 mm. 



This is one of the large West Coast Odostomias, and ranges in the recent state 

 from Alaska to San Pedro. The specimen figured is from Neeah Bay, Washington, 

 the type locality. It has six post-nuclear whorls. 



Fossil forms occur in the post-Pliocene deposits of Deadman Island, and also 

 at Ventura. 



0. avellana differs from true 0. nuciformis in having the spire much more 

 elongated; it is therefore less pudgy than that form. 



Section Chrysallida Carpenter. 



Chrysallida Cpr., Cat. Maz. Shells, p. 416, 1857. Type, Chrysallida communis C. B. Adams. 



Odostomias having strong axial ribs, crossed by equally strong spiral sculpture, which renders 

 the spire nodulose; the axial ribs pass only faintly over the base, while the spiral sculpture remains 

 quite prominent. 



