884 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvi. 



WEST AMERICAN SPECIES. 

 DOSINIA (DOSINIDIA) PONDEROSA Gray, 1838. 



Pavta, Peru, northward to the Gulf of California, and to north 

 latitude 26° 30' on the west coast of Lower California; in the Pleisto- 

 cene north to San Pedro, California. 



This, the largest and finest of the genus, recalls somewhat the 

 Atlantic D. concentrica. It is the Artemis ponderosa Gra}', 1838, the 

 Artemis gigantea Sowerby (in Philippi, 1847), and the Venus cycloides 

 Or])ignv, 1847. Artemis d/stans Sowerby, 1852, if frora Puerto 

 Potrero, Costa Rica, as suggested by Carpenter, may be identical with 

 the young of this species. 



DOSINIA (DOSINIDIA) DUNKERI Philippi, 1844. 



West Colombia, at Santa Elena; Panama Ba} ; the Galapagos Islands; 

 and northward to Mazatlan and the head of the Gulf of California; 

 also to Magdalena Bay, on the west coast of Lower California. 



This is Dosinia simplex Hanley, 1845, not of A. Adams, 1855, and 

 Cytherea pacifica. Troschel. 1845, not Venus pacijica Dillwyn, 1817. 



DOSINIA (DOSINIDIA) ANNiE Carpenter, 1857. 



Mazatlan and the Gulf of California. 



This is less tumid, more elongated and smoother than D. Dunkeri., 

 and has a more horizontal pallial sinus. The small D. nanus Reeve, 

 1850. was probably based on a very young specimen of this species. 



CLEMENTIA SOLIDA Dall, 1902. 



Topolobampo, on the west coast of Mexico; collected by E. Daniels. 



This is a large and squarish species, with a more solid shell and less 

 degenerate hinge than any of the others heretofore known. It has 

 somewhat the aspect externally of Saxidonms giganteus. 



TRANSENNELLA TANTILLA Gould, 1853. 



Sitka Harbor, Alaska, and southward to Lower California at Todos 

 Santos Bay, in 3 to 1() fathoms; also fossil in the Pleistocene of 

 Santa Barbara, California. 



Trigonal, moderately convex, rather elongate; white, with or with- 

 out zigzag brown painting, usually with the posterior dorsal slope 

 dark purple within and without. 



This species is viviparous and was referred by Carpenter to his 

 genus Psephis on that account, but has a wholly different hinge. It 

 has Ijeen referred to Venus, Trigona, etc., but on the basal margin has 

 the sulcations of Trrmsennellu , though less distinct than in the typical 

 species. The Pleistocene specimens were named Venus r/ti/som/'a by 

 Gabb in 1861. 



