52 NEW UNIONID^, MELANID^, ETC., 



late ; lateral teeth very long, lamellar and somewhat curved ; nacre silver white and 

 very iridescent, 



Proc. Acad. Nat. Sci., 1863, p. 189. 



^-a&.—River Tigris, at Bagdad, C. M. Wheatley. 



My cabinet and cabinets of C. M. Wheatley and Rev. Mr. Beadle. 

 Diam. 1'2, Length 1'6, Breadth 3-1 inches. 



Shell smooth, very oblique, inflated, swollen at the tijas, very inequilateral, some- 

 what flattened at the side ; substance of the shell very thick, thicker before ; beaks 

 prominent, swollen, incurved, terminal, slightly granulate at the tips ; ligament 

 short, thick and dark brown ; epidermis yellow or yellowish brown, shining, without 

 rays, with very distant marks of growth ; umbonial slope very much raised and 

 rounded ; posterior slope rather wide, flattened, depressed between the beaks ; cardi- 

 nal teeth erect, compressed, corrugate and crenulate ; lateral teeth very long, lamel- 

 lar and somewhat curved; anterior cicatrices distinct, very deeply impressed; poste- 

 rior cicatrices confluent, large and slightly impressed ; dorsal cicatrices placed on the 

 upper side of the cavity of the beaks ; cavity of the shell deep and wide ; cavity of 

 the beaks deep and subangular ; nacre beautifully white and very iridescent. 



Bemarhs. — I owe the possession of several specimens of this remarkable species to 

 the kindness of Mr. Wheatley. It had been supposed to be the U. Tigris, Fer., or 

 Tigridis, Bourg., but it certainly is not either of them. I have both these species in 

 my cabinet. It is very much larger than either, and although of nearly the same 

 outline, presents several distinct characteristics, such as its flattened sides and 

 remarkably recurved beaks. In outline and size it is very near to trimcatus, Swain., 

 but differs totally in the form of the cardinal teeth. Some of my specimens are 

 nearly of the size of the figures of Mr. Swainson in his Zool. Illus., 2d series. The 

 fine, erect cardinal teeth in dignatus are remarkable, being compressed and locking 

 in, as it were. The marks of growth are distant and very distinct, being broad and 

 dark brown on the yellow epidermis of the younger specimens. The nacre is very 

 much thickened at the anterior basal margin. The granulations of the tips are 

 small, in a double row and scarcely visible. 



Unio Mosulensis. pi. 17, fig. 49. 



Testa Isevi, elliptica, subinflata, valde iasequilaterali ; valvulis crassiusculis, antice crassioribus ; natibus 

 prominulis, ad apices minute undulatis ; epidermide straminea, micante, eradiata; dentibus cardi- 

 nalibus parviusculis, oorrugatis, orenulatis, in utroque valvule duplicibus ; lateralibus longis, lamel- 

 latis subrectisque ; margarita alba et iridescente. ' 



Shell smooth, elliptical, somewhat inflated, very inequilateral; valves somewhat 

 thick, thicker before ; beaks a little prominent, minutely undulate at the beaks ; 



