1914] 



English : Agasoma-like Gastropods 



253 



Vaqueros formation of Barker's Ranch, Kern County, and from the 

 Vaqueros formation in San Luis Obispo County. Therefore this form 

 is considered to be only a variety of A. barkerianum. 



Dimensions approximately the same as for A. barkerianum. 



This variety is listed from the Vaqueros of Santa Cruz Quad- 

 rangle, and from Coalinga (Arnold) ; Vaqueros (Temblor) of Kern 

 County and San Luis Obispo County (Cal. Acad. Sci. Coll.). 



AGASOMA BARKERIANUM Cooper, var. CLARKI, n. var. 

 Plate 25, figures !> and 10 



Shell of medium size, spire conieal ; whorls five ; body-whorl evenly 

 curving in outline, the upper slope being nearly continuous with slope 

 of the spire: suture impressed, bordered by raised carina; early 

 whorls cancellated; body-whorl ornamented by fine spiral lines; gen- 

 erally four or five of these lines are more prominent than the others, 

 and along them are distributed about twenty, small, horizontally 

 elongated tubercles; outer lip simple; canal nearly straight. 



This variety is similar to both A. barkerianum and var. santa- 

 cruzanum. Its shape is nearly identical with the former, but the 

 carina is less flaring, is divided into round, evenly spaced tubercles, 

 and is prominent on the last whorl only; the tubercles on the body- 

 whorl are smaller but more regular. From the latter, A. b. var. clarki 

 differs in having tubercles on body whorl, and var. santacruzanum is 

 slightly less ventricose. 



Height 30 mm., width 21 mm.; spire height 12 mm. 



This variety is found somewhat above the Agasoma gravidum zone 

 of the Monterey Group in the Contra Costa Hills (Univ. Calif. Loc. 

 1352). 



Transmitted April SO, 1914. 



