EXPLANATION OF PLATE 3 



Fig. 1. Pecten tolmani Hall and Ambrose, X 1, showing convex left valve. 

 This species has never before been figured. It was first described by Hall and 

 Ambrose in Nautilus, vol. xxx, p. 82, 1916. Type is in Stanford University 

 Paleontological Collection. Specimen figured is No. 12367, Univ. Calif. Mus. 

 Pal., loc. 3581. Briones. 



Fig. 2. Modiolus gabbi subconvexus, n. var. X 1. Type. — No. 12372, Univ. 

 Calif. Mus. Pal., loc. 793. Briones. 



Fig. 3. Pecten tolmani Hall and Ambrose, X 1, showing flat right valve. 

 Specimen figured is no. 12366, Univ. Calif. Mus. Pal., loc. 3581. Briones. 



Fig. 4. Modiolus veronensis, n. sp. X 1. Type. — No. 12373, Univ. Calif. 

 Mus. Pal., loc. 3529. Briones. 



Fig. 5a. Cyrena diabloensis, n. sp. X 1. Exterior view. Type. — No. 12374, 

 Univ. Calif. Mus. Pal., loc. 1949. San Pablo. 



Fig. 5b. Cyrena diabloensis, n. sp., X 1, showing dentition. Type. 



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