158 



been found. Compared to the C. gigantea it is rather more in- 

 flated, the beaks are higher and it is not quite so truncated 

 posteriorly. 



Cyclas solidula. C. testa solida, brevi, forti, compacta 

 subglobosa, inequilaterali, postice elongata, striis incrementi for 

 titer et regulariter instructa, umbonibus rotundatis non approxi 

 matis. Dentes cardinales parvi, laterales acuti, fortes. Long 

 0.60; lat. 0.44; diam. 0.26 inches. Hah. Ohio. (Adams 

 Agassiz.) 



Shell heavy and compact. Color dark chestnut, striations 

 deep and regular. Interior, bluish. Teeth strong and well 

 developed. 



Remarks. This species appears to be very common in Ohio, 

 and has, as well as the C. distorta Nobis, been labelled C. simi- 

 lis Say. 



Comparing it to the C. similis, found in Massachusetts, Ver- 

 mont, and Pennsylvania, I find it is much more elevated, less 

 elongated and stronger ; the striations are also deeper and more 

 regular. The hinge margin is rather spherical, whereas in the 

 C. similis it is nearly on a straight line, the teeth themselves are 

 less elongated and more robust. 



It is unaccountable to me how this shell, which appears to be 

 found very plentifully, can have remained undescribed. It has 

 probably always been looked upon as the C. similis., or else it 

 may be the C. sulcata of Lamarck. Cabinet of the Boston So- 

 ciety of Natural History. 



Cyclas distorta. C. testa globosa, forti, solida, tumida, 

 inequilaterali, transverse rotundato-ovata, postice elongata, striis 

 incrementi fortiter instructa, umbonibus rotundatis et approxi- 

 matis. Long. 0.48; lat. 0.36; diam. 0.26 inches. Hal. Ohio. 

 (Adams, Agassiz.) 



Shell heavy, short, solid : lines of growth strongly marked. 

 Color reddish brown. Interior bluish ; teeth well developed and 

 strong. 



Remarks. This species has likewise been confounded with 

 the C. similis of Say : it is, however, very different from the 

 C. similis, found in Massachusetts, being much more compact, 

 heavier, and more inequilateral. The hinge margin is also more 



