330 CALIFOENIA ACADEMY OF SCIENCES. 



Rare in the Pliocene of Deadman Island, and in the lower San Pedro 

 series of Deadman Island and San Pedro; common in the upper San Pedro series of 

 Deadman Island, Sau Pedro, Los Cerritos, and Crawfish George's. Found in the 

 Pleistocene at Spanish Bight, and in the Pliocene at Pacific Beach, San Diego. 



Living. — Straits of Fnca to San Diego (Cooper). 



Pleistocene. — San Pedro to San Diego (Cooper): San Pedro; San Diego 

 (Arnold). 



Pliocene. — San Pedro; San Diego (Arnold). 



382. Calliostoma costatum Martyn. 



Trochus costatus Mart., Univ. Conch., PI. X, fig. 3, 1784. Philippi, Conch. Cab., p. 275, 



PI. XL, fig. 8. 

 Calliostoma cosiatiim Mart., Cpr., Brit. Assn. Rept., 1863, p. 652. Gabb, Pal. Cal., Vol. II, 



p. 83, 1869. Cooper, 7th Ann. Rept. Cal. St. Min., 1888, p. 231. Tryon, Man. 



Conch., Vol. XI, p. 362, PI. XVI, figs. 6, 9; PI. XVIII, fig. 16, 1889. Keep, West 



Coast Shells, p. 81, fig. 66, 1892. Williamson, Proc. U. S. Nat. Mus., Vol. XV, 



1892, PI. XXII, fig. I. 

 Zizyphinus filosus Wood, Reeve, Conch. Icon., fig. 27. 



Shell turbinated, thick; whorls five, convex, and ornamented with about eight, almost equally 

 prominent, spiral ridges; fine oblique incremental lines visible on most specimens; suture deeply 

 impressed; base slightly convex, ornamented same as whorls; outer lip slightly effuse; columella 

 thickened and incrusted. 



Dimensions. — Alt 22 mm.; lat. 20 mm.; defl. 70 degrees. 



Distinguishable by the even convexity of the whorls, numerous, comparatively 

 smooth, spiral ridges, and thickness of the shell, which is unusual for a member of 

 this genus. 



Rare in the lower San Pedro series of Deadman Island and San Pedro; and 

 in the upper San Pedro series of Crawfish George's, Los Cerritos, and San Pedro. 

 Found in the Pleistocene at Pacific Beach, San Diego. 



Living. — Sitka to San Diego (Cooper). 



Pleistocene. — San Pedro to San Diego (Cooper) : San Pedro; San Diego 

 (Arnold). 



Pliocene. — San Fernando, Los Angeles County (Cooper). 



383. Calliostoma gemmulatum Carpenter. 



Calliosloma gemniulaliun Cpr., Brit. Assn. Rept., 1863, p. 653; Proc. Cal. Acad. Sci., Vol. Ill, 

 1864, p. 215. Cooper, 7th Ann. Rept. Cal. St. Min , 1888, p. 231. Tryon, Man. 

 Conch., Vol. XI, p. 371, PI. LXVII, fig. 54, 1889. Keep, West Coast Shells, p. 81, 

 1892. Williamson, Proc. U. S. Nat. Mas., Vol. XV, 1892, PI. XXII, fig. 3. 



Spire more acute than in other species of the genus; whorls six to seven, concave above, 

 convex below; convex part has two or three rows of granular spiral ridges; concave surface orna- 

 mented with a few fine granular spiral ridges; suture indistinct; base flat, marked by several smooth 

 spiral ridges; aperture circular. 



Dimensions. — Alt. 18 mm.; lat. 15 mm.; defl. 46 degrees. 



