,»' 



The Nautilus. 



Voi-. XIII. MARCH, 1900. No. 11. 



NOTE ON PETRICOLA DENTICULATA Sby. 

 i:v \v. n. DALL. 



The enquiry suggested by me in the Nautilus for January (p. 

 100) has been quickly answered. Mrs. Oldroyd has kindly forwarded 

 to me three specimens of Pttricola from Long Beach, Cab, collected 

 by Mrs. Blood, which solve the problem as to the adult form of Car- 

 penter's Psepkis tellimyalis beyond all shadow of a doubt. The little 

 brown radiated nepionic shells appear with astonishing distinctness 

 against the white shell of the adult Petricola. What is still more 

 curious is that these dark-colored tips must fade, as in all the museum 

 series extending from San Pedro to Peru not a single one retains the 

 color, and one of Mrs. Blood's specimens has very little. There ;ire 

 two species of Petricola, belonging to the section Petricolaria Stol- 

 iczka, on the coast of California, neither of which jjoes much north 

 of San Pedro. One is the elongate P. cognata C. B. Adams (the 

 analogue of the east coast P. pholadiformis), also named gracilis by 

 Deshayes. The other has the following synonymy, and very likely 

 more. 



Petricola denticulata Sowerby. 

 P. denticulata Sby. P. Z. S., 1X34, p. 47. 



P. ventricosa (Deshayes Ms. J Sowerby, Thes. Conch., p. 773, pi. 

 166, figs. 6, 7, 1S;">4 (in synonymy). 



P. nivea Sowerby op. cit., p. 773, pro parte, not of Gmelin, 1792. 

 P. tenuis Sowerby 1834, ('. B. Adams and others, pro parte. 



