THE NAUTILUS. 



VOL. XXVII. MARCH, 1914. No. 11 



NOTES ON SOME WEST AMERICAN PECTENS. 



BY WILLIAM H. DALL. 



Since publishing iny notes on West Coast Pectens in 1898, in the 

 Transactions of the Wagner Institute, a very large amount of ma- 

 terial has accumulated which enables me to revise and correct the 

 nomenclature then adopted and the views of relationship of the dif- 

 ferent forms treated. The complete work is reserved for future pub- 

 lication, some notes however having an immediate interest. 



In 1839 Anton described under the name of Pectan excavatus a 

 species from China afterward named by Sowerly P. sinensis. This 

 is a good species. In '1846 the plate of the Mollusca of the u Voyage 

 of the Venus " by Valennciennes were issued and contain a Pecten 

 named P. excavatus. Whether the name is a mere coincidence, or 

 the species was supposed to be the same as Anton's, cannot be known, 

 as the text was never published. At any rate the shell figured was 

 identical with that commonly known as P. dentatus G. B. Sowerby, 

 1 842. But there is a P. dentatus described by J. Sowerby in 1829, so 

 that the name of 1842 cannot be used. For this common species of the 

 Gulf of California I propose the name of Pecten (Euvola) cataractes. 



The group of Pectens including P. islandicus Miiller, P. ruhidus 

 Hinds (= hindsii Cpr. ), P. hastatus Sowerby, P. hericius Gould, etc. 

 has always puzzled writers, all of whom, including myself, have been 

 misled by worn specimens or insufficient material. 



Possessing the types of Gould, Carpenter, and Arnold, and a full 

 series of the recent shells in good condition, 1 have reached the fol- 

 lowing conclusions. 



