EXPLANATION OF PLATE 13 



Fig. 1. Tellina oregonensis Conrad. No. 11191, Coll. Invert. Palae. Univ. 

 Calif., loe. 14. Natural size. 



Fig. 2. Nucula postangulata, n. sp. No. 11194, Coll. Invert. Palae. Univ. 

 Calif., loe. 1131. Approximately twice natural size. 



Fig. 3. Acila muta marldeyensis, n. var. Type, no. 11195, Coll. Invert. Palae. 

 Univ. Calif., loe. 1131. Approximately twice natural size. 



Fig. 4. Tellina oregonensis Conrad. A very well preserved specimen of 

 left valve, no. 11192, Coll. Invert. Palae. Univ. Calif., loc. 1131. Natural size. 



Fig. 5. Nucula postangulata, n. sp. Type, no. 11260, Coll. Invert. Palae. 

 Univ. Calif., loc. 2754. Approximately twice natural size. 



Fig. 6. Acila muta, n. sp. Type no. 11196, Coll. Invert. Palae. Univ. Calif., 

 loc. 1131. Natural size. 



Fig. 7. Acila shumardi Dall. Posterior view showing escutcheon; specimen 

 from the California Academy of Sciences collection, obtained from the type 

 locality, from which the type of this species came, on the bluffs along the Nehalem 

 River, near the town of Pittsburg, Oregon. Natural size. 



Fig. 8. Acila shumardi Dall. Lateral view of right valve of same specimen 

 as fig. 7. Natural size. 



Fig. 9. Acila gettyshurgensis Reagan. Left valve of specimen collected by 

 Professor C. E. Weaver. Natural size. 



Fig. 10. Cyathodonta weaveri, n. sp. No. 11193, Coll. Invert. Palae. Univ. 

 Calif., loc. 1131. Natural size. 



Fig. 11. Cardium dickersoni. No. 11198, Coll. Invert. Palae. Univ. Calif., 

 loc. 1131. Natural size. 



Fig. 12. Acila muta, n. sp. A small specimen enlarged about twice natural 

 size. No. 11199, Coll. Invert. Palae. Univ. Calif., loc. 1131. 



Fig. 13. Acila muta, n. sp. No. 11200, Coll. Invert. Palae. Univ. Calif., loc. 

 199. Natural size. 



Fig. 14. Pccten (Pseudomuseum) alterlineatus, n. sp. Type, no. 11202, Coll. 

 Invert. Palae. Univ. Calif., loe. 1131. Nearly twice natural size. 



Fig. 15. Pectcn {Pseudomuseum) alterlineatus, n. sp. No. 11203, Coll. Invert. 

 Palae. Univ. Calif., loc. 1131. Approximately twice natural size. 



Fig. 18. Cardium dickersoni, n. sp. Type, no. 11207, Coll. Invert. Palae. 

 Univ. Calif., loc. 2755. Natural size. 



Fig. 17. Acila shumardi Dall. No. 11207, Coll. Invert, Palae. Univ. Calif., 

 loe. 78. Natural size. 



Fig. 18. Cardium diclcersoni, n. sp. Type, no. 11207, Coll. Invert. Palae. 

 Univ. Calif., loc. 1131. Three times natural size. 



Fig. 19. Anomia inconspicua, n. sp. Type, a left valve, no. 11205, Coll. 

 Invert. Palae. Univ. Calif., loc. 1131. Approximately twice natural size. 



Fig. 20. Anomia inconspicua. A right valve, showing large unclosed byssal 

 sinus. No. 11204, Coll. Invert. Palae. Univ. Calif., loc. 1131. Approximately 

 twice natural size. 



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