THE NAUTILUS. 



VOL. XIII. MARCH, 1900. No. 11. 



NOTE ON PETRICOLA DENTICULATA Sby. 



KY \V. H. DA LI,. 



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

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

 to me three specimens of Petricola from Long Beach, Cal., collected 

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

 penter's Psephis teUiiiiyalis 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 are 

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

 icxka, on the coast of California, neither of which goes 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 

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

 more. 



PETKICOLA DENTICULATA Sowerby. 



P. defiticiiliitu Sby. P. Z. 8., 1*34, p. 47. 



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

 Kit!, figs. 6, 7, 1S54 (in synonymy). 



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

 P. tennis Sowerby IS: 1 ^, C. B. Adams and others, pro pnrte. 



