^°i89a"'J PROCEEDINGS OF THE NATIONAL MUSEUM. 219 



and furthermore agrees in every respect with the description. C. pectun- 

 cuius is included in Lister's Conch. Hist., Oxonioe, 1770, PI. 347, Fig. 

 185, and is the Chania pectnnculus of Dillwyn, etc. 



C. californica is nothing more than a varietal form of affinis, and the 

 alleged distinctions fade away or blend gradually when a large series 

 are placed side by side for comparison. 



A form nearly related to the foregoing and closely resembling indi- 

 viduals of the afinis-californica aspect is the C. radiafa Brod. (1832), 

 in Reeve's Monograph, PI. 1, Fig. 5, collected at Panama and elsewhere 

 along the coast of the same general region. Two specimens in the 

 National Museum (No. 1590G) were determined by Cuming as this 

 species; one of them, upon careful examination proves to be the com- 

 mon a finis of Panama, the other agrees closely with Eeeves's figure, 

 above noted, in form, color, etc., as well as with the description. 



I should have included it, with perhaps a passing comment, with the 

 other three, had it not had the initials of Mr. Cuming on tlie label, 

 which led me to scrutinize it closely. There is a difference in the shape 

 and direction of the central cardinal tooth in the left valve, which, if 

 varietal, is certainly rather an unusual aspect of variation, and may be 

 regarded more properly as abnormal, if the many other characters 

 which connect with the forms previously named should be allowed to 

 outweigh this single differential feature. 



Carpenter's little " Lazaria suhquadrata,^^ of the upper Californiau 

 l)rovince, comes in here. It is an interesting form, combining the coarse 

 exterior ribbing and aspect of the laticostata group, with the hinge 

 characters of Varditamera. 



The peculiarly interesting form upon which Mr. Dall has made the 

 genus Milneria, with one species, minima, completes the list of West 

 American Carditas, which may be summarized as follows: 



C. Cuvieri Brod. 



C. flammed Mich., + C varia Brod., + C. tiimida Brod. 



C. crassa Gray. 



C. laticostata Sby., + C. tricolor Sby. 



C. (Venericardia) ventricosa Gould, -f- ? C. occidentalis Conr., + ? C. subtenta Conr., the 



last two fossils. 

 C. ( Venericardia) borealis Conr. 

 C. ( Venericardia) barbarensis Stearns. 

 C. {Miodon) prolongatus Cpr. 



C. {Cardiiamera) pectnnculus Brug., + affinis Sby., + californica Desh. 

 C. {Carditamera) subquadrata Cpr. 

 C. (Milneria) minima Dall. 



Doubtful and imperfectly described or figured, perhaps in some in- 

 stances synonyms of the foregoing. 



C. monilicosta Gabb. 



C. (Venericardia) compressa Hve., ? = borealis Conr. 



C. (? Venericardia) fiabellum Eve. 



C. semen Eve. 



C. tegulata Eve. 



C. (Carditamera) radiata Brod. ? = pectunculus var. 



