776 PROCEEDINGS OF THE NATIOXAI, MUSK I'M. VOL. xxn. 



(Group of Quadrula lachrymosa.) 



Shell quadrate or rhomboid, generally with a sharp, well-developed 

 posterior ridge, in front of which is a wide, shallow, radial excavation ; 

 base incurved, posterior end sharply truncate, generally slightly bian- 

 gular below, high and distinctly angled behind the ligament; posterior 

 tubercles often in somewhat radiating rows; earlier beak sculpture 

 consisting of ridges nearly parallel with the growth lines, but later on 

 becoming doubly looped and blending into the general sculpture of the 

 shell; epidermis smooth; pseudocardinals strong; laterals straight; 

 nacre white. 



Animal with all four gills used as a marsupium throughout, inner 

 much the larger, free from the abdominal sac nearly or quite their whole 

 length ; palpi very large; branchial opening generally having clustered, 

 often branching papillae; anal opening smooth; superanal opening 

 closed below. 



fQUADRULA ASPER Lea. 



* Unio asper LEA, Tr. Am. Phil. Soc., IV, 1831, p. 85, pi. ix, fig. 15 ; * Obs., I, 1834, 



p. 95, pi. ix, fig. 15. * CONRAD, New F. W. Shells, 1834, p. 67. *HANLEY, 

 Test. Moll., 1842, p. 179; * Biv. Shells, 1843, p. 179, pi. xxn, fig. 37. "CATLOW 

 and REEVE, Conch. Norn., 1845, p. 56. * CONRAD, Pr. Ac. N. Sci. Phila., VI, 

 1853, p. 245. *H. and A.ADAMS, Gen. Rec. Moll., II, 1857, p. 497. *CUENU, 

 111. Conch., 1858, pi. xv, figs. 4, 4a, 46; * Manual, 1859, II, p. 142, fig. 695. 



* REEVE, Conch. Icon., XVI, 1864, pi. v, fig. 18. *B. H. WRIGHT, Check List, 

 1888. 



* Margarita (Unio) asper LEA, Syn., 1836, p. 15; 1838, p. 15. 



* Margaron ( Unio) asper LEA, Syn., 1852, p. 22; 1870, p. 33. 



* Unio noUlis CONRAD, Jl. Ac. N. Sci. Phila., II, 1854, p. 297, pi. xxvn, figs. 2, 3. 



* Unio iurgidus REEVE, Conch. Icon., XVI, 1864, pi. in, fig. 10. 



* Unio apiculatus var. asper PJETEL, Conch. Sam., Ill, 1890, p. 144. 



Streams flowing into the Gulf of Mexico from Alabama west to cen- 

 tral Texas, and northward to the Verdigris Eiver, Kansas. 



tQUADRULA LACHRYMOSA Lea. 



Unio lacnrymosus LEA, Tr. Am. Phil. Soc., Ill, 1828, p. 272, pi. vi, fig. 8; ' Obs., I, 

 1834, p. 14, pi. vi, fig. 8.* SHORT and EATON, Transylvania JL, 1831, p. 76. 

 *FERUSSAC, Guer. Mag., 1835, p. 27. *HANLEY, Test. Moll., 1842, p. 177; 

 *Biv. Shells, 1843, p. 177, pi. xx, fig. 38. *CATLOW and REEVE, Conch. Nom., 

 1845, p. 60. *H. and A. ADAMS, Gen. Rec. Moll., II, 1857, p. 497. *CHENU, 

 111. Conch., 1858, pi. xv, figs. 6, 6a, 6&; Manual, 1849, II, p. 142, fig. 6<)8. 



* REEVE, Conch. Icon., XVI, 1864, pi. ix, fig. 33. *B. H. WRIGHT, Check 

 List, 1888. *P;ETEL, Conch. Sam., Ill, 1890, p. 156. 



* Margarita ( Unio) lachrymosus LEA, Syu., 1836, p. 14; 1838, p. 15. 



* Margaron ( Unio} lachrymosus LEA, Syn., 1852, p. 21 ; 1870, p. 32. 



* Unio lachrymosus KUSTER, Conch. Cab., 1854, p. 70, pi. xva, fig. 3. 



1 Published as a separate in 1827. 1 have not seen this. Title from Sabin's Biblio- 

 theca America. 



