32 



pustules, These are very evident on the front. Cos* 

 tal arches simple, or not grooved. Length, one inch 

 and three-fourths, breadth of the buckler one inch 

 and one-fourth. 



This species resembles a little the C. Pulchella of 

 Dalman. The specimen from which the model was 

 taken, is in the possession of Mr. R. Peale, of New 

 York, who willingly lent it for this monograph. He 

 informed me that it was found in the state of New 

 York, but he was unable to name its precise locality. 

 It occurs in a soft ash coloured limestone. No other 

 petrifaction is observable in the fragment of rock 

 which contains it. 



CALYMENE PLATYS.* Green. Casts No. 4 and 5. 



Clypeo antice rotundatoj prominentia frontal! 

 utrinque quatuor tuberculis. 



The buckler is probably semilunatej but as the an- 

 terior portion is lost, this cannot be determined with 

 precision. The posterior raised rim is not continu- 

 ous, as in the C. Selenecephala> but is separated by 

 the longitudinal dorsal furrows. The front is distinct* 

 ly divided from the cheeks, and has four tubercular 

 prominences on each side. Three of them are near- 

 ly on a line with the lateral edge of the cheeks, and 

 gradually diminish in size, as they descend to the 

 anterior part of the buckler. The other is smaller, 

 and is between, and a little to the side, of the upper 



* From a Greek work which signifies Flat, 



