"658 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxu. 



Animal witli the outer gills larger than the inner behind, narrower in 

 front, inner free from the abdominal sac, all united to the mantle nearly 

 to their posterior i)oiuts; mantle double edged; branchial opening large, 

 a lew irregular, large and small branched papillne on it; anal opening 

 large, with rudimeutary papillse; superanal opening closed a long way 

 below; foot very large when living. !No ova were found in the 

 branchi.TB in numerous specimens taken at different dates and localities, 



t GONIDEA ANGULATA Lea. 



*Anodonta angnlata Lea, Tr. Am. Phil. Soc, VI, 1838, p. 97, pi. XVI, fig, 52; ** Obs., 

 II, 1838, p. 97, pi. XVI, fig. 52.— *Troschel, Arch, fiir Nat., V, 1839, Pt. 2, p. 

 239.— ^^Hanley, Test. Moll., 1842, p. 222; *Biv. Shells, 1843, p. 222, pi. xxiv, 

 fig. 15.— ^GOULD, U.S. Expl. Exp., XII, 1852, p. 436.—* Conrad, Pr. Ac. Nat. 

 Sci. Phila., VI, 1853, p. 263.— "H.aDcl A. Adams, Gen. Eec. Moll., II, 1857, p. 

 504.— * Chenu, Man., 1859, II, p. 146, fig. 722.— *Eeeve, Elem. Conch., II, 1860, 

 pi. XXXI, fig. 180. — Clessin, Conch. Cab. Ano., 1874, p. 159, pi. on, figs. 3, 4. — 

 ^ B. H. M^EiGHT, Check List, 1888.—* P.etel, Conch. Sam., Ill, 1890, p. 176. 



^Margarita (Anodonta) angulata Lea, Syu., 1838, p. 32. 



^Marqaron {Anodonta) angulata Lea, Syn., 1852, p. 52; 1870, p. 83. 



"Anodon angulata Caltow and Reeve, Couch. Nora., 1845, p. 66. 



*Anodon anguJatas Sowerby, Conch. Icon., XVII, 1867, pi. in, fig. 6. 



' \ Anodon feminalis Gould, Pr. Bost. Soc. N. Hist., Ill, 1850, p. 293; *Otia Conch., 

 1862, p. 87. 



''Anodonta feminalis Gould, U. S. Expl. Exp., XII, 1852, p. 436, figs. 547, 547^, 

 5476. — *H. and A. Adams, Gen. Eec. Moll., II, 1857, p. 502. — *P,«tel, Couch. 

 . Sam., Ill, 1890, p. 179. 



"Anodonta randalli Trask, Pr. Cal. Ac. N. Sci,, I, 1855, p. 29. — * PyETEl, Couch. 

 Sam., Ill, 1890, p. 177. 



"Anodon hiangnlata Sowerby, Conch. Icon., XVII, 1869, jd. xxiii, figs. 8, 8a, 8&. 



"Anodonta hiangulata Clessin, Conch. Cab. Auo., 1876, p. 234, pi. lxxvii, fig. 3. 



Central California; north to British Columbia; east to Idaho. 



Genus ANODONTOIDES Simpson (in Baker) 1898. 



(Type, Anodonta fentssaciana Liea,.)' 



Anodoniopsis Simpson (in Baker), Tr.- St. Louis Ac. Sci., VIII, 1898, p. 76; not 



Anodontopsis McCoY. 

 Anodontoides Simpson (in Baker"), Moll. Chicago, 1898, p. 72. 



Shell elliptical, inflated, thin, with a faint posterior ridge, sometimes 

 constricted at the center of the base; beaks rather full, with 'a. few 

 coarse, subparallel, concentric ridges, which are curved up rather 



'The shells of this group are much like those of Strophitus, but have different beak 

 sculpture. The character of the marsupia is also difierent in the two genera. In 

 this group a limited number of ovules was found in the inner gills of one of the few 

 gravid specimens seen, while in Anodonta only the outer gills contain ova so far as 

 I have observed. It differs from Anodonta in the curving in of the hinge line in 

 front of the beaks, in the beak sculpture, and in having papillae on the anal open- 

 ing. Notwithstanding the fact that I have found embryos in all four gills of a 

 specimen of this genus, I have placed it with the Homogente rather than with the 

 Tetrageiipe because the characters of shell and animal seem to agree better with the 

 former than with the latter. 



