ARNOLD — THE PALEONTOLOGY AND STRATIGKAPHT OF SAN PEDRO. 335 



the peninsula of Lower California, and is in the Tertiary belt. This would corres^oond 

 to the horizon of the formation at Deadman Island, where they are found only in the 

 Pliocene. The specimen figured is from the Pliocene of Deadman Island, and is now 

 in the collection of Delos Arnold. 



Living. — Neeah Bay to Catalina Island (dredged) (Cooper). 



Pleistocene. — San Marcial (Carpenter). 



Pliocene. — San Pedro (Arnold; Williamson). 



391. Solariella peramabilis Carpenter. 



Plate VII, Fio. 2. 



Solariella peramabilis CpR., Brit. Assn. Rept., 1863, p. 653. Cooper, 7th Ann. Rept. Cal. St. Min., 

 1888, p. 265. Tryon, Man. Conch., Vol. XI, p. 312, PI. LXVII, figs. 59-61, 1889. Will- 

 iamson, Proc. U. S. Nat. Mus. , Vol. XV, 1892, p. 202. 



Shell small, conical; spire elevated, subacute; whorls five, conve.x, with narrow tabulate band 

 just anterior to suture, and ornamentation of five or six spiral ribs crossed by fine lirulae; suture 

 deeply impressed; aperture circular; umbilicus open, large, with three internal spiral lines. 



Dimensions. — Alt. 14.5 mm.; lat. 12 mm.; body-whorl 10.2 mm.; aperture 5 mm.; defl. 

 82 degrees. 



The specimen described was identified by Dr. Dall. 



Rare in the Pliocene; four specimens found in the Pliocene of Deadman 

 Island. The specimen figured is from the Pliocene of Deadman Island, and is now 

 in the collection of Delos Arnold. 



Living. — Catalina Island (30 fathoms) (Williamson). 



Pliocene. — San Pedro (Arnold). 



Family LXXXV. CYCLOSTREMATIDiE. 

 Genus Vitrinella C. B. Adams. 

 Shell minute, depressed turbiniform; widely umbilicated; aperture large, rounded. 

 Vitrinella anomala d'Orb. is a characteristic species. 



392. Vitrinella williamsoni Ball. 



Vitrinella ivilliamsoni Dall, Proc. U. S. Nat. Mus., Vol. XV, 1892, p. 202, PL XXI, figs. 2 and 3. 



" Shell small, white, depressed, with two and a half whorls; spire flattened; suture appressed, 

 with a shallow channel or excavation outside of the appressed margin of the whorl, outside of which 

 the convexity of the whorl rises higher than the suture; base slightly more rounded than the upper 

 side, with a wide and flaring umbilicus; periphery rounded; aperture rounded, oblique; surface pol- 

 ished, finely striated here and there by the incremental lines, which are most prominent above. 



"Dimensions. — Maximum diameter of shell, 5.5 mm.; minimum diameter, 4.5 mm.; alti- 

 tude, 1.25 mm." 



