EXPLANATION OF PLATE 12 



Fig. 1. Mytilus arnoldi, n. sp. Type, no. 11153, Coll. Invert. Palae. Univ. 

 Calif., loc. 78. Natural size. 



Fig. 2. Thracia condoni Dall. No. 11168, Coll. Invert. Palae. Univ. Calif., 

 loc. 517. Natural size. 



Fig. 3. Mdlletia packardi, n. sp. Type, no. 11154, Coll. Invert. Palae. Univ. 

 Calif., loc. 2033. Natural size. 



Fig. 4. MacrocaHista weaveri, n. sp. Type, view showing dorsal areas, no. 

 11155, Coll. Invert. Palae. Univ. Calif., loc. 1134. Natural size. 



Fig. 5. Cardium kirkerensis, n. sp. Type, a wax cast, no. 11165, Coll. Invert. 

 Palae. Univ. Calif., loc. 2033. Natural size. 



Fig. 6. Biplodonta stephensoni, n. sp. Type, no. 11171, Coll. Invert. Palae. 

 Univ. Calif., loc. 1131. 



Fig. 7. MacrocaHista wcaveri, n. sp. Same specimen as fig. 4, lateral view 

 of left valve, natural size. 



Fig. 8. Yoldia cooperi tenuissima, n. var. An immature individual. No. 

 00000, Coll. Invert Palae. Univ. Calif., loc. 1309. Natural size. 



Fig. 9. Lcda ramonensis, n. sp. Type, no. 11167, Coll. Invert. Palae. Univ. 

 Calif., loc. 1131. Natural size. 



Fig. 10. Nucula? bifida, n. sp. Type, view of dorsal areas, no. 11184, Coll. 

 Invert. Palae. Univ. Calif., loc. 331. Approximately three times natural size. 



Fig. 11. Nucula? bifida, n. sp. Lateral view of left valve of same specimen 

 as figs. 10 and 11; approximately twice natural size. 



Fig. 12. Nucula? bifida, n. sp. Lateral view of right valve of same specimen 

 as figs. 10 and 11; approximately twice natural size. 



Fig. 13. Tellina praecuta, n. sp. Type, no. 11166, Coll. Invert. Palae. Univ. 

 Calif., loc. 14. An interior cast, natural size. The external ribbing is very simi- 

 lar to that of Tellina ienuilweata, n. sp. 



Fig. 14. Yoldia cooperi tenuissima, n. var. No. 11163, Coll. Invert. Palae. 

 Univ. Calif., loc. 2754. Natural size. 



[210] 



