96 [Assembly 



extending usually more than half the entire length, and leaving 

 a shallow cavity between the outer shell and the partition which 

 sometimes extends nearly to the margins on either side, but is 

 occasionally contracted by the junction of the septum with the 

 outer shell at a distance from the margin. 



I conceive that these forms are quite distinct from the Belle- 

 ROPHON ; while, in the character and substance of the shell, I can 

 see no reason to unite them with the Cleodora. I therefore pre- 

 fer for them the generic name of Clioderma. 



CLIODERMA (new genus). 



Shells more or less arcuate, somewhat calyptraeform, subtrian- 

 gular or oval, with the apex marginal and incurved in the 

 same plane, not known to be convolute, carinate upon the back, 

 abruptly and broadly expanding, with the anterior margin 

 sinuate; interior concave, much wider than deep. A concave 

 shelly partition covers the posterior half or more of the cavity. 

 Substance of the shell of moderate thickness, lamellose, with 

 surface lamellose-striate parallel to the exterior margins or 

 lines of growth. Shells heretofore referred to Cleodora, 

 Spirifer, &c. 



CLIODERMA SAFFORDI (n.s.). 



Shell arcuate ; apex much incurved : exterior form ovate-trian- 

 gular ; the sides, from the apex to the middle, somewhat 

 straight or slightly concave, rounded below, with a deep 

 sinuosity in front. Dorsum strongly carinate ; the substance 

 of the shell being bent abruptly outward, so that the carina- 

 tion affects the form of the internal cavity. Shell-partition 

 extending from the apex two-thirds the length of the shell, 

 regularly concave on the exterior side, and without apparent 

 carina on the lower side. Surface strongly lamellose-striate. 

 "Width about one inch and a half; nearly the same length. 



Geological formation and locality. In Lower Silurian strata : Lebanon, 

 Tenn. From Prof. J. M. Safford. 



