AKN'OI.D — THE PALEONTOLOGY AND STUATUiUAI'H V OP SAN PEDKO. 329 



Genus Calliostoma Swainson. 



Shell trochiform, conical, not umbilicated; last whorl angulated and usually ribliedat tiie 

 periphery; aperture quadrangular; columella simple, oblique, often ending in a tooth in front. 



Cnlliostomn zizyphimnn Linn, is a characteristic species. 



380. Calliostoma annulatum Murlyn. 



Trochus annulatiis M.-VRT., Univ. Conch., Vol. I, fig. 33, 1784. Philippi, Conch. Cab., p. 11, 



PI. Ill, figs. 3, 4. 

 Zizyphinus annu/atus Mart., A. Ads., Proc. Zool. Soc, 1851, p. 164. Gray, Diefifenbach's 



N. Zealand, p. 237, No. 72. 

 Calliostoma annulatum Mart., Cpr., Brit. Assn. Rept., 1863, p. 652. Gabb, Pal. Cal., Voi. II, 



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



Conch., Vol. XI, p. 363, PI. LXVII, fig. 43, 1889. Keep, West Coast Shells, p. 79, 



fig. 64, 1892. Williamson, Proc. U. S. Nat. Mus., Vol. XV, 1892, PI. XXII, fig. 2. 



Shell conical; whorls seven, slightly angulated in center, and ornamented with sharply 

 nodose spiral ridges which increase by intercalation from two on third whorl to seven or eight on 

 body-whorl; suture deep, distinct; body- whorl acutely angulated at base; base nearly flat, ornamented 

 with, numerous smooth, rounded spiral lines; aperture subquadrate; columella nearly straight, 

 thickened. 



Dimensions. — Alt. 17 mm.; lat. 16 mm.; defl. 67 degrees. 



Distinguishable by slightly angulated whorls, nearly equally prominent nodose 

 ridges, and nearly straight columella. 



Quite rare in the upper San Pedro series of San Pedro. 



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



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



Pliocene. — San Diego well (Dall). 



381. Calliostoma canaliculatum Martyn. 



Trochus canaliculatus Mart., Univ. Conch., Vol. I, fig. 32, 1784. 



Zizyphinus canaliailatus Mart., Gray, DiefTenbach's N. Zealand, p. 327. Reeve, Conch. Icon., 



fig. 18. 

 Calliostoma canaliculatum 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. X, PI. XLI, fig. 34, 1888; Vol. XI, p. 361, PI. LXVII, fig. 49, 1889. 



Keep, West Coast Shells, p. 80, fig. 65, 1892. Williamson, Proc. U. S. Nat. Mus., 



Vol. XV. 1892, PI. XXII, fig. 6. 



Shell conical; whorls six, flat, ornamented with very prominent rounded, spiral ridges, two 

 on the third and fourth whorls, and then increasing by intercalation until the body-whorl in some 

 specimens has five or six prominent ridges, with a less number of auxiliary riblets in between; suture 

 deeply impressed, forming a canal; aperture subquadrate; base flat, and ornamented in the same way 

 as the whorls; lip as in C. costatum. 



Dimensions. — Long. 19 mm.; lat. 20 mm.; defl. 67 degrees. 



Distinguishable by flat whorls, sutural canal, and few large spiral ridges. 



( 42 ) April 29, 1903. 



