616 PRO C EBBING S OF THE NA TIONA L MUSE UM. vol. xxii. 



Genus STROPHITUS Rafinesque, 1820. 



(Type, Anodonta undulata Say.) 



Strophitus Rafinesque, Ann. Gon. Sci. Pliys. Brux., 1820, p. 316. 

 ■ Uniopsis Agassiz, Arch, fiir Naturg., 1852, p. 49. 



Shell elliptical to rhomboid, inflated, subsolid, pointed or biangu- 

 late behind, with a low posterior ridge, which is sometimes double;- 

 beaks full, sculpture consisting of a few strong, concentric ridges, 

 which curve sharply upward behind; epidermis rayed or rayless, shin- 

 ing; hinge line incurved in front of the beaks; teeth rudimentary, a 

 vestigeal, compressed tooth in each valve, and sometimes a secondary 

 tooth; laterals rarely present; muscle scars shallow. 



Animal with the marsupium occupying the whole of the outer gills, 

 consisting of short, horizontal ovisacs which run directly across the 

 gills, and are discharged through the outer wall with the ovules in 

 them; ovules ten to twenty- five in each ovisac, in one or two rows; inner 

 gills the larger, free in part from the abdominal sac, or wholly united; 

 mantle generally bordered behind with square, black spots; branchial 

 opening with numerous papillae; anal opening papillose or crenulate.^ 



' t STROPHITUS EDENTULUS Say. 



Alcmnodonta edentula Say, N. Harm. Diss., II, No. 22, 1829, p. 340. — * Conrad, 

 New F. W. Shells, 1834, p. 72.—* L. W. Say, Terr, and Fluv, Shells, 1840, 

 p. 10. 



* Anodonta edentula Ferussac, Guer. Mag., 1835, p. 25. — * Hanley, Test. Moll., 



1842, p. 218.— *H. and A. Adams, Gen. Rec. Moll., II, 1857, p. 502.—* Calk- 

 ins, Pr. Ottawa Ac, 1874, p. 50.—* Clessin, Conch. Cab. Ano., 1873, p. 107, 

 pi. XXX, figs. 5, 6.—* Latchpord, Tr. Ottawa F. N. Club, 1882, p. 55.—" B. H. 

 Wright, Check List, 1888.— *P.etel, Conch. Sam., Ill, 1890, p. 179. 



"^ Margarita (Anodonta) edentula Lea, Syn., 1836, p. 450; 1838, p. 30. 



"Anodon edentula Catlow and Reeve, Conch. Nom., 1845, p. 66. — * De Kay, Zool. 

 N. Y., Pt. 5, 1848, p. 201, pi. xvi, fig. 231.—* Hartman and Michener, Conch. 

 Cest., 1874, p. 95, fig. 174. 



* Uyiiopsis edentula Agassiz, Arch, fiir Naturg., 1, 1852, p. 49. 

 *Margaron (Anodonta) edentula Lea, Syn., 1852, p. 49; 1870, p. 79. 



*Stro2Mtus edentulus Conrad, Pr. Ac. N. Sci. Phila., VI, 1853, p. 263. — * Baker, 



Moll. Chicago, Pt. 1, 1898, p. 67, pi. xii, figs. 5, 6 ; xvii, fig. 3. 

 *Anodon rugostis Swainson, Zool. 111., 1st ser., II, pi. xcvi, 1822. 



* Anodonta rugosus Hanley, Biv. Shells, 1843, p. 217. 



"" Anodonta undulata Hildreth, Am. Jl. Sci., XIV, 1828, p. 290. — * Clessin, Conch, 



Cab. Ano., 1873, p. 79, pi. xxvii, figs. 3, 5. 

 ""Anodon undulata Gould, Inv. of Mass., 1841, p. 120, fig. 79; 1870, p. 182, fig. 482. 

 *Unio undulata Desha yes, Tr. Elem., II, 1853, p. 217, pi. xxx, figs. 8, 9. 

 ""Anodon nndulatus Sowerby, Rich. Faun. Bor. Am., Ill, 1836, p. 316. — * Sowerby, 



Conch. Icon., XVII, 1867, pi. xi, fig. 30. 

 *Anodon areolatus Swainson, Zool. 111., 2d ser., I, 1829, pi. xviii. 

 ^Anodonta areolatus Ferussac, Guer. Mag., 1835, p. 25. 



1 In this remarkable group of mollusks the changes that take place in the gills 

 when they are used as a marsupium only last as long as they are gravid. AVhen the 

 short ovisacs are discharged the gill becomes an ordinary gill again. 



