nI 



130 PALEONTOLOGY. 



JUEASSIO SPECIES. 



MOLLUSOA. 



LAMELLIBRANCHIATA. 



LIMID^. 



Genus LIMA, Bruguifere, 

 Lima (Limatula) eeecta, Meek. 



Plate 12, fig. 2. 



Shell, exclusive of the small ears, vertically narrow-elliptic, or about 

 once and a half as high as the antero-posterior diameter, moderately con- 

 vex, and not in the slightest degree oblique ; hinge shorter than the breadth 

 of the shell, and ranging at right angles to the vertical diameter of the 

 valves; ears small, compressed, almost exactly equal, and obtusely angular; 

 beaks small, nearly exactly central, and slightly incurved without any appar- 

 ent obliquity. Surface marked with fine radiating lines, which seem to 

 show some tendency to gather into a few distant larger costse, near the nar- 

 rowly-rounded basal margin ; a few obscure undulations of growth are also 

 seen crossing the striae. 



Greatest vertical diameter, 0.72 inch; breadth, or anterior-posterior 

 diameter, 0.50 inch; convexity of one valve, about 0.10 inch. 



I only know this species from a single specimen, showing none of its 

 internal characters; and, owing to the fact that it is not in the slightest 

 degree oblique, it is impossible to determine whether it is a right or a left 

 valve. It is remarkable for its narrow form, equal ears, and want of 

 obliquity. Owing to the fineness of its striae, and the fact that they are 

 obsolete from a little below the middle to the beak, I have been unable to 

 see whether or not they are divaricating along the middle, as in some spe- 

 cies of Limatula^ though they seem not to be so from their direction below. 



Locality and position. — New Pass, Desatoya Mountains, Nevada; appar- 

 ently from the horizon of the Lower Lias. 



