700 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxii. 



* Unio hrevirostris KusTEi;, Conch. Cab. Uuio, 1854, p. 120, pi. xxxiii, figs. 1-3. — 



■ Westerlund, Faun. Pal., IJ, Pt. 7, 1890, p. 96. 



* Unio natoUcus Kuster, Conch. Cab. Unio, 1856, p. 144, pi. XLii, fig. 4. . 



* Unio tnrcicus Kuster, Couch. Cab. Unio, 1862, p. 267, pi. xc, figs. 3, 4. 



* Unio merdiger Reeve, Conch. Icon., XVI, 1865, pi. xxviii, fig. 145.' 



Europe ; Asia Minor ; Northwest Africa. 



Section lAPIDOSUS Simpson, 1900. 

 (Type, I^nio lajndosiis Kobelt.'^) 



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

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

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

 thick pseudocardinals 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. 



*Unio Japidosns Kobelt, Nach Deuts. Mai. Ges., 1893, p. 151; *Icon., new ed., 

 VI, 1893, p. 90, pi. CLXXVi, fig. 1120.— *Dkouet, .11. de Couch., XLIII, 1895, 

 p. 32. 



Euphrates River. 



Section EllIPTIO Rafinesque, 1819. 

 (Type, Unio crassidens Lamarck.) 



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

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

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

 surface smooth or ieebly corrugated. 



(Group of Unio color atus.) 



Shell somewhat rhomboid, solid, slightly biangulate behind, rather 

 comi^ressed, 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. 



?i UNIO COLORATUS Charpentier. 



* Unio colorattis Charpentieh, iu Kuster, Conch. Cab. Unio, 1856, p. 155, pi. xliv, 



fig. 6.— * Pii':TEL, Conch. Sam., Ill, 1890, p. 148.— *Fischer and Crosse, 

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



Medellin Eiver, Vera Cruz, Mexico. 



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

 Waltz. 



■^This striking shell difters very much from any of the circummediterraueau forms 

 and may be entitled to subgeneric rank. 



