8 AMERICAN CORBICULAD^E. 



Cyrena moreauensis, M. & H. Proc. Ac. N. S. Phil. 1856, 115. 

 Corbicula moreauensis, M. & H. Id. Oct. I860, 432. 



&quot; Each of the cardinal teeth has, in its upper end, a small notch 

 which is occupied, when the valves are closed, by a small projec 

 tion between the teeth of the other valve. The anterior lateral 

 tooth appears to be larger and approaches the central teeth more 

 nearly than the posterior. Our specimens are generally more or 

 less worn, and thickly coated with firmly adhering sand. Found 

 in a sand-bed, near Moreau River, associated with bones of Ti- 

 tanotherium ? Probably a distant outlier of the White River 

 bone beds.&quot; M. & H. 



10. CorMcula nelbrascensis, MEEK and HAYDEN. &quot;Shell oval- 

 ovate, compressed, rather thin ; extremities rounded ; base semi-elliptical ; 

 beaks moderately elevated, not gibbous, placed nearly half way from the 

 middle to the anterior end ; surface marked with fine lines of growth, oc 

 casionally rising into obscure concentric wrinkles ; edge of the cardinal 

 border thin ; cardinal teeth close under the beaks, posterior one very 

 oblique.&quot; 



Long. 0.76 ; Lat. 0.68 ; Diarn. 0.22 inch. 



Hub. North America, near Moreau River, Nebraska. Tertiary forma 

 tion. (Cabinet of Smithsonian Institution.) 



Cyrena intermedia, M. & H. (preoc.), Proc. Ac. N. S. Phil. 1856, 



116 (not C. intermedia, Melville, 1843). 

 Corbicula nebrascensis, M. & H. Proc. Acad. Oct. 1860, 432. 



&quot; This species approaches some varieties of C. pisum, but is 

 more inequilateral, the posterior end being comparatively longer, 

 the beaks are also less elevated. From the G. moreauensis it 

 will be distinguished by its shorter and more rounded form, more 

 elevated beaks, and much thinner cardinal edge. &quot; M. & H. 



11. CorMcula Occident alls, MEEK and HAYDEN. &quot;Shell sub- 

 triangular, very thick, rather ventricose ; anterior end and base rounded, 

 posterior end sloping abruptly from the beaks, and ventrically subtrun- 

 cate at the extremity ; beaks located a little in advance of the middle, 

 and elevated, pointed, incurved and approximate ; surface marked with 

 strong lines of growth.&quot; 



Long. 1; Lat. 1 ; Diam. 0.71 inch. 



Hab. North America, at the Bad Lands of the Judith, Nebraska. Ter 

 tiary formation. (Cabinet of the Smithsonian Institution.) 



Cijrena occidentalis, M. & H. Proc. Ac. N. S. Phil. 1856, 116. 

 Corbicula occidentalis, M. & H. Id. Oct. 1860, 432. 



