ON MOLLt'SCA OF THE WEST COAST OF NOKTH AMERICA. 



637 



Family Pholadidce. 



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



12. Pholadidea pcnita, Conr. Ilanl. &Vici. = concamerata, Desk. Shape from elongate 



to ovoid ; umbonal reflexion closely adherent. 



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



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



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



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



16. ParaplioJas Californica, Conr. Hani. auct. = P. Janellii, Desh. Very large; 



with layers of thin, short cups. 



Family Saxicavidee. 



17. Saxicava plioladis, Linn. auct.-|-var. arctica, Linn. auct. Maz. Cat. no. 234-var. 



gastrochcenoidea, ovoid and gaping like Maz. Cat. no. 21+var. leynmen, Desh., 

 elongate, cylindrical, scarcely gaping. 



18. Ghicinwris geuerosa, Gld. E.E. Perhaps = Pawop«a Faajasii, S.Wood, Crag 



Moll. : pipes like Saxicava. 



Family Myadce. 



19. Mya truncata, Linn. auct. = M. jjrcecisa, Gld. 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 illf?/a ; mantle-bend nearly 



obsolete. 



Subfamily LidrarinfB. 



22. Schizothcerus Nttttalli, Coiw. -\-Tresus inaximt(s, Midd. Gray = Z. canax, 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 Machcera. Cartilage-pits produced, gaping. 



Family Corhtdidce. 



24. Corbula hifeoln, n. s. Shape of young biradiata ; small, ashy yellow. Com. Q». 



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



26. Ne(pra pectinata, n. s. Principal ribs about 12: beak smooth. Like sidcata, 



40-60 fm. Cp, 



123 



