148 University of California Publications in Geology [Vol. 13 



It differs from L. whitmani Dall 18 in that it possesses finer and more 

 evenly distributed ribs over the entire surface, the posterior dorsal 

 edge is less concave, and the shell appears much narrower. 



Family Pectinidae 

 Genus PECTEN Midler 

 PECTEN (LYROPECTEN) RICEI, n. sp. 

 Plate 2, figures 1 and 2 



Type.— No. 12364; cotype— No. 12365, Univ. Calif. Mus. Pal. 



Shell medium in size; about as long as high, equilateral; apical angle about 

 89°; anterior and posterior dorsal margins strongly depressed; surface of left 

 valve with fourteen low flat topped to broadly rounded ribs; interspaces flat, 

 about equal in width to ribs, and possessing from three to four, almost invariably 

 three, small riblets, which have a tendency to become bifurcated near the 

 ventral margin. 



Dimensions. — Type specimen U. C. no. 12364; alt., 63.7 mm.; width, about 

 53 mm.; apical angle, 89°. Cotype, U. C. no. 12365; alt., 72.3 mm.; width, 70.7 

 mm.; apical angle, 93°. 



Occurrence. — Briones formation. Type from U. C. loc. 3535; cotype from 

 loe. 3534. 



Named in honor of Professor C. D. Eice, University of Texas. 



PECTEN (LYROPECTEN) VICKERYI, n. sp. 

 Plate 4, figure 1 

 Type in Stanford University Paleontological Collection. 



Shell large, slightly more wide than high; ears about one-half the width of 

 the shell; dorsal margins strongly depressed and quite long, being about three- 

 fourths the height of the shell; surface with sixteen prominent ribs; every third 

 rib being higher and more strongly developed than the others; interspaces about 

 as wide as ribs; both ribs and interspaces ornamented with numerous fine 

 riblets; ears with five to six small ribs. 



Dimensions. — Alt., 99 mm.; width about 106 mm.; apical angle, 100°. 



Occurrence — Briones formation, vicinity of McGuire Peaks, Pleasanton 

 Quadrangle. 



Note. — Only one valve has been found. Type specimen possesses depression 

 near ventral margin. 



Named in honor of Mr. Frederick P. Vickery, Department of Geology, South- 

 ern Branch, University of California. 



PECTEN (PECTEN) RAYMONDI BRIONIANUS, n. var. 

 Plate 1, figures 2 and 3 



Type— No. 12368; cotype— No. 12369, Univ. Calif. Mus. Pal. 



Dimensions. — Type specimen U. C. no. 12368; alt., 37.3 mm.; width, 37.3 mm.; 

 length of ears, 18.7 mm.; apical angle, 100°. Cotype, U. C. no. 12369; alt., 

 31.7 mm.; width, 32.7 mm.; apical angle, 100°. 



Occurrence. — San Pablo group. Type and cotype from U. C. loc. no. 3532. 



is Dall, U. S. G. S. Prof. Paper 59, p. 103, pi. XIV, fig. 4, 1909. 



