252 NEW UNIONID^, MELANID^, ETC., 



Unio Mardinensis. pi. 30, fig. 66. 



Testa liBvi, suboblonga, inEequilaterali, autice rotundata, postice obtuse angulata ; valvulis subtenui- 

 bus, antics crassioribus ; natibus prominuiis, ad apices crebre et minute undulatis ; epidermide 

 luteola, valde radiata ; dentibus cardiualibus parvis, acuminatis crenulatisque ; lateralibus sub- 

 longis subrectisque ; margarita aurea et valde iridescente. 



Shell smooth, subobloug, inequilateral, rounded before, obtusely angular behind ; 

 valves rather thin, thicker before ; beaks slightly prominent, closely and minutely 

 undulate at the tips; epidermis yellowish and much rayed; cardinal teeth small, 

 acuminate and crenulate; lateral teeth rather long and nearly straight; nacre golden 

 and very iridescent. 



Proc. Acad. Nat. Sci. 1864, p. 286. 



Hah. — Tigris River near Mardin, Asiatic Turkey, C. M. Wheatley. 



My cabinet and cabinet of Mr. Wheatley. 

 Diam. -8, Length 1-2, Breadth 1-9 inch. 



Shell smooth, suboblong, inequilateral, rounded before, obtusely angular behind ; 

 substance of the shell rather thin, thicker before; beaks slightly prominent, closely 

 and minutely undulate at the tips; ligament rather short and light brown; epider- 

 mis 3'ellowish and much rayed on the posterior portion, with rather distant lines of 

 growth ; urabonial slope rounded ; posterior slope raised and usually dark green ; 

 cardinal teeth small, acuminate and crenulate; lateral teeth rather long and nearly 

 straight; anterior cicatrices distinct and well impressed; posterior cicatrices con- 

 fluent, large and very slightly impressed ; dorsal cicatrices placed above the centre of 

 the cavity of the beaks ; cavity of the shell rather deep and wide ; cavity of the beaks 

 subangular ; nacre golden and very iridescent.. 



Bemarlis. — Quite a number of specimens of different ages are before me. The 

 younger ones are perfect in the beaks, which display a number of irregular wrinkles, 

 which vary somewhat in different specimens. The cardinal tooth is double in the 

 left and treble in the right valve. The nacre is rich, being usually golden and satin 

 like. In nearly all the specimens the posterior portion is covered with dark green 

 rays. It is nearly allied to KuIIethensis, herein described, but that shell is more in- 

 equilateral, has a less elevated posterior slope and is a thicker shell. 



MoNOCONDTLGEA Maedinensis. PL 30, fig. 67. 



Testa Isevi, arcuata, valde insaquilaterali, ad latere compressa, antice et postice rotundata ; valvulis 

 crassiusculis, antice crassioribus ; natibus subprominentibus, recurvis, ad apices minute undulatis ; 

 epidermide tenebroso-fusca ; dentibus cardinalibus parvis, erectis compressisque ; margarita 

 c£eruleo-alba et iridescente. 



Shell smooth, arcuate, very inequilateral, compressed at the sides, rounded before 



and behind ; valves rather thick, thicker before; beaks a little prominent, recurved 



