572 PROCEEDINGS OF THE NATIONAL MUSEUM. voL.xxn 



LAMPSILIS ALIENIGENUS Crosse and Fischer. 



* Unio alienigenusCROsSKandFisciiFAi, Jl. dbConcli., XLI, 1893, p. 294. — * Fischer 

 and Crosse, Miss. Sci., Pt. 7, II, 1894, p. 590, pi. ixv, figs. 5, 5a; lxvi, fig. 3. 



Goatzalcoalcos, Vera Cruz, Mexico.^ 



(Group of LampsUis aztecoriim.) 



Shell elliptical, obloug, rounded in front and behind, the posterior 

 part being slightly compressed, the whole rather thin; umbonal region 

 inflated; beak sculpture unknown; epidermis brown and rather smooth; 

 pseudocardinals small, laterals curved; nacre purple and shining; 

 female shell (the specimen figured) somewhat swollen in post basal 

 region, so that the basal line is slightly incurved. 



Animal unknown. 



LAMPSILIS AZTECORUM Philippi. 



*Unio aztecoriim Philippi, Zeits. fiir Mai., IV, 1847, p. 95; ''Abbikl., Ill, 1849, p. 



109, pi. VI, fig. 2.— *KUSTER, Conch. Cab. Unio, 1862, pp. 2, 84, pi. xcv, fig. 



6.— *B. H. Wright, Check List, 1888.— "^ P^tel, Couch. Sam., Ill, 1890, p. 



145.— * Fischer and Crosse, Miss. Sci., Pt. 7, II, 1894, p. 607. 

 *Margaron ( Unio) aztecoriim Lea, Syn., 1870, p. 44. 



(Group of Lmnpsilis metallicus.) 



Shell rather small, obovate-rhomboid, inflated, much narrowed and 

 rounded in front, the form approaching that of a Modiolus; epider- 

 mis a rich coppery bronze, shining; beak sculpture consisting of two 

 faint, rounded loops, the bars of which are inclined to be nodulous; 

 pseudocardinals compressed, not Avell developed, and sometimes more 

 or less broken into denticles; laterals distinct; pits in the beak cavity 

 numerous and very irregular; nacre dark, coppery to purple, with 

 metallic tints, iridescent behind. Animal unknown. 



t LAMPSILIS METALLICUS Say. 



Unio metallicus Say, N. Harm., Disseminator (newspaper form), January 15, 1831 ; 

 *Am. Conch ., VI, 1834.—" Conrad, New F. W. Shells, 1834, p. 70.—* Ferussac, 

 Guer. Mag., 1835, p. 29.—" L. Say, New Terr, and Fluv. Shells, 1840, p. 6.— 

 * Conrad, Pr. Ac. N. Sci. Phila., VI, 1853, p. 252.—^ P,«tel, Conch. Sam., Ill, 

 1890, p. 159. 



t* Utiio cupriiius Lea, Tr. Am. Phil. Soc, IV, 1831, p. 94, pi. xii, fig. 24; - * Obs., I, 

 1834, pi. XII, fig 24.—* Hanley, Test. Moll., 1842, p. 208 ; * Biv. Shells, 1843, p. 

 208, pi. XXII, fig. 7. — *Cati.ow and Reeve, Conch. Nom., 1845, p. 58. — *Cheni', 

 111. Conch., 1858, pi. xi, figs. 3, 3a, 3h. — *H. and A. Adams, Gen. Rec. Moll., 



' I am considerably in doubt as to the relationship of the last two species. Fischer 

 and Crosse are sure that alienigenus is close to nmbrosiis, and their figure and descrip- 

 tion seem to show that explicatus is near to alienigenus. 



2The Transactions of the Philosophical Society, IV, in which Mr. Lea published 

 his Unio cuprinns, which is identical with Mr. Say's species, was issued, according to 

 Scudder, in the latter end of 1831. 



