ON MOLLUSCA OP THE WEST COAST OF NORTH AMERICA. 



637 



Family Pholadidfe. 



11. Zirphesa crispata, Linn. auct. E. & W. Atlantic and circumpolar. 



12. Pholadidea penita, Conr. Hani. auct. = concamerata, Desh. Shape from elongate 



to ovoid ; umbonal reflexion closely adherent. 



13. Pholadidea ovoidea, Gld. Otia. Umbonal reflexion with anterior opening. 



14. Netastoma Darwinii, Sby. New submenus : valves prolonged, like duck's bill 



instead of cups. Surface with concentric frills. Quoted from " S. A." 



15. Martesia intercalata, Cpr. Maz. Cat. no. 19. From Southern fauna. 



16. Parapholas Californica, Conr. Hani. auct. = P. Janellii, Desh. Very large j 



with layers of thin, short cups. 



Family Saxicavida. 



17. Saxicava pholadis, Linn. auct.-J-var. arctica, Linn. auct. Maz. Cat. no. 23-f-var. 



gastrochcenoidea, ovoid and gaping like Maz. Cat. no. 21-fvar. legumen, Desh., 

 elongate, cylindrical, scarcely gaping. 



18. Glycimeris generosa, Gld. E.E. Perhaps = Panopcea Faujasii, S. Wood, Crag 



Moll. : pipes like Saxicava. 



Family Myada. 



19. Mya truncata, Linn. auct. = M. prcecisa, Gld. v Atlantic : circumpolar. 



20. Platyodon cancellatus, Conr. Hani. Pipe-ends 4-valved. Low water : common. 



Sold in S. Francisco market, Cp. 



21. Cryptomya Californica, Conr. Outside like young Mya; mantle-bend nearly 



obsolete. 



Subfamily Lutrarinee. 



22. Schizotharus Nuttalli, Conr. -f Tresvs maximus, Midd. Gray=Z. capax, Gld. 



Shape from ovoid to elongate ; very large and tumid ; beaks swollen ; hinge- 

 sides channeled ; mantle-bend joined to ventral line. 



23. Darina declivis, n. s. Outside like Macheera. Cartilage-pits produced, gaping. 



Family Corbulida. 



24. Corbula luteola, n. s. Shape of young biradiata ; small, ashy yellow. Com. Cp. 



25. Sphania ovoidea, n. s. Siphonal area small ; front excurved ; mantle-bend large. 



26. Necera pectitwta, n. s. Principal ribs about 12 : beak smooth. Like sulcata, 



40-60 fm. Cp. 



123 



