1916] 



Packard: Mesozoic and Cenozoic Mactrinae 



313 



SPISULA(?) WEAVERI Packard 

 Plate 27, figure 9 



Spisula ('!) weaveri Packard, Dickerson, Univ. Calif. Publ. Bull. Dept. 

 Geol., vol. 8, p. 139, pi. 12, figs. 4«, 46, 1914. 



Packard described this species as follows: 



Shell small, relatively thick, subtrigonal to oval, moderately ventricose, 

 evenly rounded; umbones nearly central, prosogyrate, prominent, nearly 

 adjacent; anterior dorsal margin concave for a distance equal to about one- 

 third the height of the shell; anterior extremity slightly attenuated, evenly 

 rounded; base broadly rounded, curving gently in the dorsal region to the 

 beak; surface roughened by coarse lines of growth; hinge and interior but 

 imperfectly known. The dimensions of the type are: length, 32 mm., height, 

 26 mm., convexity, 5 mm. 



There is considerable variation in the outlines of this species. 

 A specimen doubtfully compared to this species was noted in the 

 collections of the Scripps Institution for Biological Research from 

 the Tejon of Rose Canon, San Diego County. It clearly shows the 

 impressions of a spisuloid dentition. 



The type was obtained from the Martinez near Stewartville, 

 Contra Costa County, at University of California Locality 1556, 

 which may be described as follows: NE 14 of NW Vt of Sec. 15, T 

 1 N, R 1 E, a little over one mile south of Stewartville, ten feet 

 above the Martinez Chico contact. 



Occurrence. — Eocene: Lower Martinez, Mount Diablo region, 

 California. 



Species Not Valid 



MACTRA ( ?) GABIOTENSIS Conrad 



Mactra(t) gabiotensis Conrad, Pac. R. R. Reports, vol. 7, p. 194, pi. 7, 

 fig. 3, 1854-55. 



The description of this species was based upon a cast of a fossil 

 specimen obtained from Gaviota Pass, California. Its general out- 

 line is comparable to several Miocene mactrine species and there- 

 fore it must be declared an invalid species. 



