768 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. xxn. 



ADAMS, Gen. Rec. Moll., II, 1857, p. 498. * REEVE, Conch. Icon., XVI, 1864, 



pi. ix, fig. 35.* B. H. WRIGHT, Check List, 1888.* P.ETEL, Conch. Sam., Ill, 



1890, p. 163. 



*Margaron ( Unio) perplicatus LEA, Syn., 1852, p. 20 ; 1870, p. 29. 

 * Plectomerus perplicatus CONRAD, Pr. Ac. N. Sci. Phila., VI, 1853, p. 261. 

 t *Unio atrocostatiis LEA, Tr. Am. Phil. Soc., X, 1848, p. 70, pi. n, fig. 5; 1 * Obs., 



IV, 1848, p. 44, pi. n, fig. 5.* H. and A. ADAMS, Gen. Rec. Moll., II, 1857, 



p. 497. *B. H. WRIGHT, Check List, 1888. * P^TEL, Conch. Sam., Ill, 1890, 



p. 145. 



*Margaron ( Unio) atrocostatus LEA, Syn., 1852, p. 20; 1870, p. 29. 

 t* Unio pearlensis CONRAD, Tr. Am. Phil. Soc., VII, 1855, p. 256. 2 * REEVE, Conch. 



Icon., XVI, 1864, pi. xi, fig. 42. 



* Unio perlen sis P.ETEL, Conch. Sam., Ill, 1890, p. 163. 



t*E7nio brazosensis LEA, Pr. Ac. N. Sci. Phila., XII, 1868, p.144; 3 * Jl. Ac. N. Sci. 



Phila., VI, 1869, p. 309, pi. XLVIII, fig. 122; * Obs., XII, 1869, p. 69, pi. XLVIII, 



fig. 122.* B. H. WRIGHT, Check List, 1888. 

 *Margaron ( Unio) brazosensis LEA, Syn., 1870, p. 31. 

 i*Unio lincecumii LEA, Pr. Ac. N. Sci. Phila., XII, 1868, p. 144; * Jl. Ac. N. Sci. 



Phila., VI, 1869, p. 312, pi. XLIX, fig. 125; * Obs., XII, 1869, p. 72, pi. XLIX, fig. 



125.* B. H. WRIGHT, Check List, 1888. 

 *Margaron ( Unio) lincecumii LEA, Syn., 1870, p. 31. 

 *Unio lincecurii P.ETEL, Conch. Sam., Ill, 1890, p. 157. 4 

 \*Unio pauciplicatus LEA, Pr. Ac. N. Sci. Phila., II, 1872, p. 156; * Jl. Ac. N. Sci. 



Phila., VIII, 1874, p. 29, pi. ix, fig. 26; *Obs., XIII, 1874, p. 33, pL ix, fig. 



26.* B. H. WRIGHT, Check List, 1888. 



tQUADRULA PERPLICATA var. QUINTARDII Cragin. 5 



* Unio quintardii CRAGIN, Bull. Washb. College, II, 1887, p. 6. * PILSBRY, Pr. Ac. 



N. Sci. Phila., 1892, p. 131, pi. vn, figs. 1-3.* B. H.WRIGHT, Check List, 1888. 



Alabama River drainage and streams flowing into the Gulf of Mexico 

 west to central Texas, north to southern Kansas. 



tQUADRULA ELLIOTTII Lea. 6 



*Unvo ellioltii LEA, Pr. Ac. N. Sci. Phila., VIII, 1856, p. 262; *J1. Ac. N. Sci. 

 Phila., IV, 1858, p. 54, pi. vn, fig. 37; *Obs., VI, 1858, p. 54, pl.vn, fig. 



1 This seems to be merely a form of perplicata, with a rather rude growth and 

 roughened epidermis. 



2 A comparatively smooth form of perplicatus, according to the type. 

 s Another smooth form of perplicatus. 



4 The above is a fair sample of Pietel's orthography throughout his work. 



5 A right valve of the type was kindly loaned to the writer by Mr. Quintard. It 

 is a rather light brown, glossy shell, and is sculptured with a series of yy-shaped 

 markings on the disk. Otherwise it is generally like Q. perplicatus. I have seen 

 the Q. undulata and one or two other species of this group break from the ordinary 

 oblique bars into these peculiar markings, and I am quite sure that in this case the 

 same thing has happened to Q. perplicata. 



6 Dr. Lea first called this Unio atrocostatus, and then wrote in one of his duplicates 

 Unio elliottii. He says that it is very near to U. perplicatus Conrad, but that the 

 young of his species have a yellow stain on the posterior part of the nacre not found 

 on any other species. I have, however, found it on young atrocostatus in his collec- 

 tion. I am strongly inclined to believe that the elliottii is only a peculiar, vigorous 

 variety of perplicata, but do not feel quite certain of it, and so let it go as a species 

 with doubt. 



