NO. 1205. SYNOPSIS OF THE XAIADES— SIMPSON. 775 



tQUADRULA SPARSA Lea. 



*Unio sparsus Lea, Pr. Am. Phil. Soc, II, 1841, p. 82 ;;^ *Tt. Am. Phil. Soc, VIII, 

 1842, p. 242, pi. XXV, fig. 58; *0b8.. Ill, 1842, p. 80, pi. xxv, fig. 58.— * Con- 

 rad, Pr. Ac. N. Sci. Pliila., VI, 1853, p. 257.—* H. and A. Adams, Gen. Eec. 

 Moll., II, 1857, p. 497.— *Chenu, 111. Conch., 1858, pi. xxvi, figs. 2, 2a, 21.— 

 * Reeve, Conch. Icon., XVI, 1864, pi. iv, fig. 14. — * B. H. Wright, Check List, 

 1888.— * PjlTel, Conch. Sam., Ill, 1890, p. 168. 



* Margaron (Unto) sparsus Lea, Syu., 1852, p. 22; 1870, p. 33. 



Holston aud Clinch rivers, Tennessee. 



tQUADRULA INTERMEDIA Conrad. 



* Unio intermedins Conrad, Monog., VII, 1836, p. 63, pi. xxxv, fig. 2; *Pr. Ac. 



N. Sci. Phil., VI, 1853, p. 250.—* Hanley, Biv. Shells, 1856, p". 381, pi. xx, 

 fig. 28.— *H. and A. Adams, Gen. Eec. Moll., II, 1857, p. 497.— * Kuster, 

 Conch. Cab. Unio, 1861, p. 213, pi. Lxx, fig. 6.— ■ Eeeve, Conch. Icon., XVI, 

 1864, pi. XIII, fig. 48.—* B. H. Wright, Check List, 1888.—* P.etel, Conch. 

 Sam., Ill, 1890, p. 155. 



* Margaron ( Unio) intermedius Lea, Syn., 1852, p. 22; 1870, p. 33. 



* Unio Ideinianm Kuster, Conch. Cab. Unio, 1861, p. 191, pi. lx, fig. 4. 



Tennessee River system. 



tQUADRULA STAPES Lea. 



* Unio sta]}es Lea, Tr. Am. Phil. Soc, IV, 1831, p. 77, pi. vii, fig. 8.—* Obs., I. 



1834, p. 87, pi. VII, fig. 8.—* Conrad, New F. W. Shells, 1834, p. 71.—* Fer- 

 ussac, Guer. Mag., 1835, p. 28.—* Coxrad, Monog., VII, 1836, p. 62, pi. xxxv, 

 fig. 1.—* Hanley, Test. Moll., 1842, p. 179; * Biv. Shells, 1843, p. 179, pi. 

 XXII, fig. 38. — * Catlow and Eeeve, Conch. Nom., 1845, p. 64. — * Conrad, 

 Pr. Ac. N. Sci. Phila., VI, 1853, p. 258.—* H. and A. Adams, Gen. Eec. Moll., 

 II, 1857, p. 497.— Chenu, 111. Conch., 1858, pi. xv.,figs. 5, 5«, 5&; * Manual, 

 1859, II, p. 142, fig. 997.—* Eeeve, Conch. Icon., XVI, 1864, pi. xiii, fig. 52.— 

 *B. H.Wright, Check List, 1888.— * Pjetel, Conch. Sam., Ill, 1890, p. 168. 



* Margarita ( Unio) sta^jes Lea, Syn., 1836, p. 15; 1838, p. 13. 



* Margaron ( Unio) stapes Lea, Syn., 1852, p. 22; 1870, p. 33. 



* Unio retusus Say, Am. Conch., VI, 1834. 



* Unio stegarius Kuster, Conch. Cab. Unio, 1861, p. 211, pi. lxx, fig. 3. 



Alabama and Tombigbee rivers. 



Section THELIDERMA (Swainson, 1840) Simpson, 2 

 (Type, Unio lachrymosus Lea.) 



Shell rounded, quadrate to rhomboid, solid, pustulous ; beaks rather 

 prominent ; beak sculpture consisting of a few rather coarse, subparallel 

 ridges; anterior end rounded or slightly subtruncate above; base often 

 arcuate; i)osterior end truncate, high and angled behind the ligament; 

 epidermis scarcely rayed, never pointed ; beak cavities rather deep. 



' It is likely that this is only a small, rather smooth variety of tuberosus. 



^Swainson's first species of this group in the text of the Treatise is Unio irroratus, 

 and after this metanevrus and cylindricus. In the final classification in the same work 

 he includes in the group lachrymosus and imstulosus, and by the process of elimina- 

 tion I use the name in order to save coining a new one. 



