313 



A species of the same genus, under the above name, was described by the 

 author in the Journal of the Academy of Natural Sciences for 1856, from a 

 specimen found in the Coal-measures of Blair County, Pennsylvania. A sim- 

 ilar tooth was also described and referred to the same species in the Pro- 

 ceedings of the Academy for 1859, which was obtained by Messrs. Meek and 

 Hayden from the Upper Carboniferous formation of Fort Riley, Kansas. The 

 specimen is represented in Fig. 3, Plate XVII. 



The crown is broad, and somewhat lozenge-shaped in outline. The base 

 is bordered by a thick annulated ridge, arching downward toward the middle 

 and moderately deflected at the extremities. The free border is sharp and 

 somewhat arcuate, and the apex is slightly acuminate. The anterior sur- 

 face of the crown slopes outwardly. The posterior deeper surface is concave 

 at its lower median portion. The fang is about as long as the crown is exter- 

 nally, but is not so wide. Its extremity is angular and everted. 



The measurements of the tooth are as follows : 



Lines. 



Length of tooth in the entire condition about 19 



Breadth of crown at base - 20 



Length of crown externally 9J 



Length of crown internally . 12 



Length of fang externally 9£ 



Breadth of fang 14 



Similar teeth from the Coal-measures of Illinois have been described by 

 Professor Newberry, under the name of Petalodus destructor, in the work 

 above mentioned. Others have also been described or indicated, from the 

 Coal-measures of Indiana, Iowa, and Nebraska, by Mr. St. Johu, likewise in 

 the works above named. 



ASTERACANTHUS. 



ASTERACANTHUS SIDERIUS. 



Incidentally, I take the opportunity of describing a fossil submitted to my 

 examination by Professor J. M. S afford through Professor Hayden. It was 

 obtained near Glasgow, Tennessee, and is reputed to be of Sub-carboniferous 

 age. The specimen consists of a fragment of an ichthyodorulite, or fossil- 

 fish spine, and is represented in Fig. 59, Plate XXXII. It appears to indi- 

 cate a species of the extinct genus Asteracanthus, the remains of which had 

 previously only been found in formations of later age than that above men- 

 tioned. 



40 a 



