700 PROCEEDINGS OF Till'. .Y.l 77O.Y.I /. Ml SEUM. 



1'iiin l->-rironh-in KUSTBH, Conch. Cab. Unio, 1*51, p. 120, }>1. xxxin, figs. 1-3. 

 WKS i EKI.UND, Faun. Pal., II, Pt. 7, 1-S90, p. 5)6. 



* Unio natolicus KUSTEK, Conch. Cab. Unio, 1856, p. 144, pi. XLII, tig. 1. 

 I'niu litrnots KUSTKK, Conch. Cab. Unio, 1862, p. 267, pi. xc. ligs. 3, 4. 

 I'tiio mcrdiger KKKVK. Concb. Icon., XVI, 1865, pi. xxvin, fig. 145." 



Europe; Asia Minor; Northwest Africa. 



Section LAPIDOSUS Simpson, 1900. 

 (Type, 1'iiio Jaj>idosus Kobelt. 2 ) 



Shell inequilateral, subtriangular ovate, large, solid, slightly inflated, 

 with a double posterior ridge, triangulate behind ; beaks high, sculpture 

 not seen; disks strongly, irregularly sulcate; epidermis olive; three 

 thick psendocardinals in the right valve and two in the left; laterals 

 strong; anterior muscle scars deep, tripartite; posterior scars deep, 

 distinct; nacre rosy white, irridescent behind. Animal unknown. 



UNIO LAPIDOSUS Kobelt. 



' Cnio lapidosus KOBEI.T, Nacb Dents. Mai. Ges., 18M3, ]>. 151; *Icon., new ed., 

 VI, 1893, p. 90, pi. CLXXVI, fig. 1120. *DKOUKT, .11. <le Couch., XLIII, 1895, 

 p. 32. 



Euphrates Kiver. 



Section ELLIPTIC Rafinesque, 1819. 

 (Type, Unio crassidvns Lamarck.) 



Shell elongated, rhomboid or oval, usually more or less biangulate 

 behind; beak sculpture consisting of a few rather strong ridges, which 

 are nearly parallel to the growth lines or slightly doubly looped; the 

 surface smooth or ieebly corrugated. 



(Group of Unio coloratns.} 



Shell somewhat rhomboid, solid, slightly biangulate behind, rather 

 compressed, more or less sculptured with concentric sulcations; beaks 

 moderately prominent, their sculpture unknown; epidermis brownish; 

 teeth strong; laterals rather club-shaped; nacre white or purple. Ani- 

 mal unknown. 



?|UNIO COLORATUS Charpentier. 



* Unio coloratits CHARPENTIKK, in Knster, Concb. Cab. Unio, 1856, p. 155, pi. xi.iv, 



fig. 6. *P.KTKI., Conch. Sam., Ill, 1890, p. 148. *FisciiKH and CROSSK, 

 Miss. Sci., Pt. 7, II, 1894, p. 599. 



Medellin liiver, Vera Cruz, Mexico. 



'Credited to Jay's Catalogue, in which it is not described, but is credited to 

 Waltz. 



2 This striking shell differs very much from any of the cirrniimiediterraneau forms 

 and may be entitled to subgeneric rank. 



