1920.] NATURAL SCIENCES OF PHILADELPHIA. 327 



Thecodonta (?) symmetrica n. sp. Fig. 10. 



The shell is oval; white, very inequilateral, the beaks being nearly 

 terminal, moderately convex, basal margin more curved than the 

 dorsal. Exterior smooth except for very faint growth lines. In the 

 right valve there is a bilobed tooth in front of the beaks, low, elong- 

 ate lamina posteriorly. 



Length 2.65, altitude 1.9, diameter 1.1 mm. 



Oahu: Haleiwa on the beach, Pilsbry, 1913. 



Fig. 10. — Thecodonta (?) symmetrica. Fig. 11. — Nucula hawaiensis n. sp. 

 Nucula hawaiensis n. sp. Fig. H. 



The shell is white, broadly ovate, moderately plump, smooth 

 near the beaks, elsewhere very closely ridged with smooth, regular 

 concentric striae. Anterior end broadly rounded, posterior narrowly 

 rounded; basal margin more arcuate than the dorsal. The teeth 

 are rather short, 5 before and 10 behind. 



Length 2.8, altitade 2.2, diameter 1.5 mm. 



Oahu: Haleiwa, on the beach, Pilsbry, 1913. 



Probably immature. 



EXPLANATION OF PLATE XII. 



Fig. 1. — Terebra thaanumi n. sp. Type 117019. 



Fig. 2. — Terebra thaanumi Waikiki. 74526. 



Fig. 3. — Terebra flavofasciata n. sp. Tj^je. 46909. 



Fig. 4. — Terebra argus brachygyra n. subsp. Type. 46910. 



Fig. 5. — Terebra langfordi n. sp. Type. 117038. 



Fig. 6. — Terebra langfordi angustior n. subsp. Type. 



Fig. 7. — Terebra lanceata oahuensis n. subsp. 117041. 



Fig. 8-10. — Terebra medipacifica n. sp. Type and paratype. 117039. 



Fig. 11. — -Terebra medipacifica melior n. subsp. Type. 



Fig. 12. — Terebra waikikiensis n. sp. Type. 117030. 



Fig. 13. — Terebra spaldingi n. sp. Type. 117044. 



Fig. 14. — Mitra ticaonica vagans n. subsp. Honolulu Harbor. 



Fig. 15. — Mitra ticaonica vagans n, subsp. Type. Hilo. 46790. 



Fig. 16. — Mitra lugubris honoluluensis n. subsp. Type. 46793. 



Fig. 17. — Mitra imikikensis n. sp. Type. 46788. 



Fig. 18. — Modiolus matris n. sp. Type. 47193. 



Fig. 19. — Mitra emersoni n. sp. Type. 46804. 



Fig. 20. — Mitra langfordi n. sp. Type. 46805. 



Fig. 21. — Mitra thaanumiana n. sp. Type. 46810. 



