ON MOLLUSCA OF THE WEST COAST OF NORTH AMERICA. 



637 



Family Pholadida. 



11. ZirphfPn a-i'spata, Linn. auct. E. & W. Atlantic and circiimpolar. 



12. Pholadidea penita, Conr. Ilanl. s.\ict.=^ concameruta, Desh. Shape from elongate 



to ovoid ; unibonal reflexion closely adherent. 



13. Pholadidea onndfu, Gld. Otia. Umbonal reflexion with anterior openinof. 



14. NetaMoma Danvinii. Sby. New subgenus : valves prolonjred, like duck's bill 



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



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



16. Paraphohis Californica, Conr. Hani. auct. = P. JattelUi, Desh. Very large; 



with layers of thin, short cups. 



Family Saxicavidee. 



17. Saxicava pholadis, Linn, auct.+var. arctica, Linn. auct. Maz. Cat. no. 234- var. 



ffa.ifrochaitoidea, ovoid and gaping like Maz. Cat. no. 21+var. legumen, Desh., 

 elongate, cylindrical, scarcely gaping. 



18. Ghjcimeris getierosa, Gld. E.E. Perhaps = Pa?jop«a Faiijasii, S.Wood, Crag 



Moll. : pipes like Saxicava. 



circumpolar. 



Low water : common. 



Family Myadee. 



19. Mya truncafa, Linn. auct. = 3/. prcecim, Gld. Atlantic ; 



20. Plafi/odon cancellatus, Conr. Hani. Pipe-enda 4-valved. 



Sold in S. Francisco market, Cp. 



21. Cnjptom)ia Californica, Conr. Outside like young Mya ; mantle-bend neailj 



obsolete. 



Subfamily LutrarinoB, 



22. SchzothfPrus Nuttalli, Qnnr.-^Tresus maximus, Midd. Gray=:Z. capax, Gld. 



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

 sides channeled ; mantle-bend joined to ventral line. 



23. Danna dedivis, n. s. Outside like Machara. Cai'tilage-pits produced, gaping. 



24. Corhula, hdenln, n. s. 



25. Sphtrnia oroidca, n. 8. 



26. Neccrn pectinata, n. s, 



40-liOfm. Cp. 



Family Corhulida. 



Shape of young biradiata ; small, ashy yellow. Com. Cp, 



Sipnonal area small ; front excurved ; mantle-bend large. 



Principal nbs about 12; beak smooth. Like mkuta. 



