702 i'i;on-;i-;i>].\<;s or mi: \.rrio.\.i/. Mi'si.i M. 



256. * HANLEY, Test. Moll., 1842, p. 176; * Biv. Shells, 1843, p. 176, pi. \x, 

 fig. 32. *CATLOW and REEVE, Conch. Nom., 1845, p. 63. *KusTKii, Conch. 

 Cab., 1818, p. 142, pi. XLH, fig. 1. * H. and A. ADAMS, (Jen. Rec. Moll., II, 1857, 

 p. li7. GHENT, 111. Conch., 1858, pi. xxn, figs. 5, 5, 51>; Manual, 1859, II, 

 p. 142, fig. 702. *SO\VEKIJY, Conch. Icon., XVI. 1868, pi. LXXV, fig. 387. 

 1>. II. WRIGHT, Check List, 1888. * FISCHER and CUOSSE, Miss. Sci., II, 

 1't. 7, 1894, p. 580, pi. LXV, fig. 2; LXX, figs. 2, 2a. 

 Marnaron ( Unio) pliciferitH LEA, Syn., 1852, p. 20; 1870, p. 31. 

 Ciiio plexus CONRAD, Monog., X, 1838, p. 89, pi. XLIX, figs. 1, 2; *Pr. Ac. Nat. Sci. 

 Phila., VI, 1853, p. 255. 



Vera Cruz, Mexico. 



t UNIO CROCODILARUM Morelet. 



I 'nio crocodilarum MOREI.ET, Test. Nov., I, 1849, p. 28. " REEVE, Conch. Icon., 

 XVI, 1864, pi. x, fig. 37.* P.KTEL, Conch. Sain., Ill, 1890, p. 149.* FISCHER 

 and CHOSSE, Miss. Sci., Pt. 7, II, 1894, p. 577, pi. LX, fig. 3; LXVII, fig. 3. 

 .' / nio rnsticus SOWERBY, Conch. Icon., XVI, 1868, pi. LXIV, fig. 324. 



Rio Usuinacinta, (luatemala. 



UNIO MORINI Morelet. 



I'nio moriiii 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. 



Rio Usumacinta, Guatemala. 



UNIO SEMIGRANOSUS von dem Busch. 



* Unio semigranosus VON DEM BUSCH (in Philippi), Abbild. uud Besch., I, 1845, 



p. 19, pi. I, figs. 1-3. * CATLOW and REEVE, Conch. Nom., 1845, p. (i 1. 

 * CONRAD, Pr. Acad. N. Sci. Phila., VI, 1853, 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. Uuio, 1861, p. 252, pl.LXXXV, fig. 1. *B. H. 

 WRIGHT, Check List, 1888. v FISCHER and CROSSE, Miss. Sci., Pt. 7, II, 

 1894, p. 569. 



% Margaron ( Unio) semigranosus LEA, Syn., 1852, p. 20; 1870, p. 34. 

 I 'nio carbon a i-ius var. semirjranosus P.KTEL, Conch. Sam., Ill, 1890, p. 147. 



Mexico, Vera Cruz to Tarapico. 



t UNIO CORIUM Reeve. 1 



" Unio corium REEVE, Conch. Icon., XVI, 1864, pi. x, fig. 39. * P.KTEL, 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 lestudineus 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 nemigranosus REEVE, Conch. Icon., XVI, 1864, pi. x, fig. 36. 



Rio Usumacinta, Guatemala. 



1 Probably a mere variety of aemif/ranosus. It is quite likely that when a sufficient 

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

 to be placed in the synonymy. 



2 Fischer and C rosso think that textudincus is perhaps only a local race of semiyra- 

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



