FOSSILS OF THE WAVEELY GROUP. 253 



that it is a little wider, but not sufficiently so to be considered beyond the 

 limits of specific variation. The shell is ver)^ gibbous, in fact quite inflated 

 in form, and evenly striate. Other individuals show the large cardinal 

 process known to exist in the original, and, considering the extreme varia- 

 tions to which species of this genus are subject, we see no reason why this 

 should be considered as distinct from the typical forms. 



Formation and locality. — In limestones of the age of the Waverly group, 

 at Dry Canon, Oquirrh Mountains, Utah. Collected by S. F. Emmons, esq. 



Genus STROPHOMENA Rafinesque. 

 Strophomena KHOMBOiDALis Wilckens. 



Plate IV, fig. 4. 



For synonyma see Ptilseont. N. Y., vol. iv, p. 76. 



The examples of this species observed present a broad flattened surface 

 with but a slight geniculation, the flattened portion being covered by close, 

 rather small, or narrow, concentric wrinkles, which are crossed by fine radiat- 

 ing striae. The form is similar to those found in the yellow sandstones of 

 Burlington, Iowa. The straight hinge-line is about as long as the width oi 

 the shell below, or a little shorter, and the length of the shell about two- 

 thirds as great as the width. The geniculation is near the margin ; the 

 flattened disk occupying almost the entire extent of the shell. Only the 

 ventral valve has been observed. 



Formation and locality. — In limestone of the age of the Waverly 

 group, Dry Canon, Oquirrh Mountains, Utah. Collected by J. E. 

 Clayton, esq. 



Genus CHONETES Fischer. 

 Chonetes Loganensis n. sp. 



Plate IV, fig. 9. 



Shell of moderate size, semicircular; hinge-line straight, longer than 

 the width of the shell below; the extremities acutely angular. Ventral 

 valve convex, with a slight flattening, scarcely a depression, along the median 

 line, widening gradually toward the front; sides of the valve rounded, 



