614 PROCEEDINGS OF THE NATIONAL MUSEUM. 



fPTYCHOBRANCHUS TRINACRUS Lea. 



* Unio trinacrus LEA, Pr. Ac. N. Sci., Phila., V, 1861, p. 59; * Jl. Ac. N. Sci., Phila., 



V, 1862, p. 86, pi. xn, fig. 235; *Obs., VIII, 1862, p. 90, pi. xn, fig. 235. 

 *SOW,ERBY, Conch. Icoii., XVI, pi. LXXXI, fig. 428. *B. H.WRIGHT, Check 

 List, 1888. 



* Mar gar on ( Unio) trinacrus LEA, Syn., 1870. p. 36. 



Coosa Eiver, Alabama. 



tPTYCHOBRANCHUS GREENI Conrad. 



* Uniogreeni CONRAD, New F.W. Shells, 1834, p. 32, pi. iv, fig. 1, p. 69. *FERUSSAC, 

 Guer. Mag., 1835, p. 29. * MILLER, Syn. Nov. Gen., 1836, p. 203.* CONRAD, 

 Monog.,VIII, 1837, p. 69, pi. xxxvin, fig. 2. *HANLEY,Test. Moll.,1842, p. 191; 

 * Biv. Shells, 1843, p. 191, pi. xxiv, fig. 6.* CHENU, Bib. Conch., 1st ser., 1845, 

 p. 17, pi. in, fig. 5. *CATLOW and REE VE,Conch. Norn., 1845, p. 59. *CONRAD, 

 Pr. Ac. N. Sci. Phila., VI, 1853, p. 250.* H. and A. ADAMS, Gen. Rec. Moll., II, 

 1857, p. 494.* SOWERBY, Conch. Icon., XVI, 1866, pi. XLVII, fig. 253.* B. H. 

 WRIGHT, Check List, 1888.* PJSTEL, Conch. Sam., Ill, 1890, p. 154. 



* Margarita ( Unio) greeni LEA, Syn., 1836, p. 24; 1838, p. 1!>. 



* Margaron ( Unio) greeni LEA, Syn., 1852, p. 27; 1870, p. 42. 



t * Unio simplex LEA, Pr. Am. Phil. Soc., IV, 1845, p. 163; *Tr. Am. Phil. Soc., X, 

 1848, p. 76, pi. v, fig. 15 ; * Obs., IV, 1848, p. 50, pi. v, fig. 15.* H. and A. ADAMS, 

 Gen. Rec. Moll., II, 1857, p. 494.* B. H. WRIGHT, Check List, 1888.* P^TEL 

 Conch. Sam., Ill, 1890, p. 167. 



* Margaron ( Unio) simplex LEA, Syn., 1852, p. 27 ; 1870, p. 42. 



Black Warrior Eiver, Alabama. 



tPTYCHOBRANCHUS FLAVESCENS Lea. 



* Unio JJarescens LEA, ' Pr. Am. Phil. Soc., IV, 1845, p. 163; Tr. Am. Phil. Soc., X, 



1848, p. 72, pi. in, fig. 9; * Obs., IV, 1848, p. 46, pi. m, fig. 9.* CONRAD, Pr. 

 Ac. N.Sci. Phila., VI, 1853, p. 249. * H. and A.ADAMS, Gen. Rec. Moll., II, 

 1857, p. 494.* B. H. WRIGHT, Check List, 1888. 



* Margaron ( Unio) Jtarescens LEA, Syn., 1852, p. 27; 1870, p. 43. 



* Unio flavescens P/ETEL, Conch. Sara., III. 



Black Warrior Eiver, Alabama. 



ESCHATIGEN^E. 



Male and female shells alike; embryos in distinct, short ovisacs, 

 forming a border to the entire outer gills. 



Genus DROMUS Simpson, 19OO. 

 (Type, Unio dromus Lea. ) 



Shell solid, rounded-triangular; beaks well forward, rather high; beak 

 sculpture consisting of fine ridges running parallel with the growth 

 lines, the furrows between the ridges interrupted at the posterior ridge; 

 posterior ridge distinct; a series of humps runs from the beaks down to 

 the central part of the base of the shell, whicli is otherwise sculptured by 



1 I have only seen a single shell of this, and it is not in the best condition. It may 

 be only a form of greeni, but it is not so inflated or solid, and it has no rays. 



