702 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxii. 



256.— *PIanley, Test. Moll., 1842, p. 176; *Biv. Shells, 1843, p. 176, pi. xx, 

 fig. 32. — *Catlow and Eee>e, Conch. Nom., 1845, p. 63. — *Kustek, Conch. 

 Cab., 1848, p. 142, pi. xlii, fig. 1.— ■ H. and A. Adams, Geu. Rec. Moll., II, 1857, 

 p. 497. — *Chenu, 111. Conch., 1858, pi. xxii, figs. 5, 5a, oh; Manual, 1859, II, 

 p. 142, fig. 702.— * SowERBY, Conch. Icon., XVI, 1868, pi. lxxv, fig. 387.— 

 *B. H. Wright, Check List, 1888. — * Fischer and Crosse, Miss. 8ci., II, 

 Pt. 7, 1894, p. 580, pi. Lxv, fig. 2; lxx, figs. 2, 2a. 

 Margaron ( Unlo) pUdferus Lea, Sjni., 1852, p. 20; 1870, p. 31. 

 ■ Uitio plexus Conrad, Monog., X, 1838, p. 89, pi. xlix, figs. 1, 2; *Pr. Ac. Nat. Sci. 

 Phila., VI, 1853, p.255. 



Vera Cruz, Mexico. 



1 UNIO CROCODILARUM Morelet. 



*Unio crocodilarwm Morki.et, Test. Nov., I, 1849, p. 28. — " Reeve, Conch. Icon., 

 XVI, 1864, pi. X, fig. 37.—* P.ETEL, Conch. Sam., Ill, 1890, p. 149.— * Fischer 

 and Crosse, Miss. Sci., Pt. 7, IT, 1894, p. 577, pi. lx, fig. 3; lxvii, fig. 3. • 



* ? Unio rusticiis Sov^^erby, Conch. Icon., XVI, 1868, pi. lxiv, fig. 324. 



Kio Usumacinta, Guatemala. 



UNIO MORINI Morelet. 



* Unio inorini Morelet, Test. Nov., II, 1851, p. 24. — * Fischer and Crosse, Miss. 



Sci., Pt. 7, II, 1894, p. 576, pi, lx, fig. 2; lxvii, fig. 4. 



Eio Usumacinta, Guatemala. 



UNIO SEMIGRANOSUS von dem Busch. 



*Unio semigranosus voN dem Busch (in Philippi), Abbild. nnd Besch., I, 184.5, 

 p. 19, pi. I, figs. 1-3. — * Catlow and Reeve, Conch. Nom., 1845, p. 64. — 

 * Conrad, Pr. Acad. N. Sci. Phila., VI, 18,53, p. 257.—* Hanley, Biv. Shells, 

 1856, p. 381, pi. XX, fig. 33.—* H. and A. Adams, Gen. Rec. Moll., II, 1857, 

 p.497.— *KusTER, Conch. Cab. Unio, 1861, p. 252, pi. lxxxv, fig. 1.— *B. H. 

 Wright, Check List, 1888.—* Fischer and Crosse, Miss. Sci., Pt. 7, II, 

 1894, p. 569. 



* Margaron (Unio) semigranosus Lea, Syn., 1852, p. 20; 1870, p. 34. 



* Unio carhonarius var. semigranosus P.etel, Conch. Sam., Ill, 1890, p. 147. 



Mexico, Vera Cruz to Tampico, 



t UNIO CORIUM Reeve.i 



' Unio corium Reeve, Conch. Ic(m., XVI, 1864, pi. x, jig. 39. — * PtETEl, Conch. 

 Sam., Ill, 1890, p. 149.—* Fischer and Crosse, Miss. Sci., Pt. 7, II, 1894, 

 p. 570. 



State of Chiapas, Mexico. 



UNIO TESTUDINEUS Morelet. 



* Unio iestudineus Morelet, Test. Nov., I, 1849 p. 28.-— Fischer and Crosse, 



Miss. Sci., Pt. 7, II, 1894, p. .571, pi. lxii, fig. 3; lxx, fig. 3. 



* Unio semigranosus Reeve, Conch. Icon., XVI, 1864, pi. x, fig. 36. 



Eio Usumacinta, Guatemala. 



' Probably a mere variety of semigranosus. It is quite likely that when a su£6cient 

 amount of material is examined this and some other species of this group will have 

 to be placed in the synonymy. 



2 Fischer and Crosse think that iestudineus is perhaps only a local race of semigra- 

 nosus. I think it is quite likely they are right. 



