EXPLANATION OF PLATE 15 



Fig. 1. Pecten (Chlcmys?) gabbi, n. sp. Type, a left valve, no. 11138, Coll. 

 Invert. Palae. Univ. Calif., loc. 1311. Natural size. 



Fig. 2. Pecten (CMamys?) gabbi, n. sp. A right valve, no. 11139, Coll. 

 Invert. Palae. Univ. Calif., loc. 1311. Natural size. 



Fig. 3. Periploma vndulata, n. sp. No. 11140, Coll. Invert Palae. Univ. 

 Calif., loc. 1309. A right valve, natural size. 



Fig. 4. Periploma undulata. Type, no. 11141, Coll. Invert. Palae. Univ. 

 Calif., loc. 1309. A left valve, natural size. 



Fig. 5. Antigona (Artena) mathewsonii (Gabb). Hinge of left valve, no. 

 11142, Coll. Invert. Palae. Univ. Calif., loc. 1131. 



Fig. 6. Antigona (Artena) mathewsonii Gabb. A specimen from the collec- 

 tion of the old state survey, labeled Chione mathewsonii, from near Martinez. A 

 left valve, no. 11143, Coll. Invert. Palae. Univ. Calif., loc. 4. Natural size. 



Fig. 7. Antigona mathewsonii Gabb. No. 11144, Coll. Invert. Palae. Univ. 

 Calif., loc. 14. Natural size. 



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