﻿304 G^BB'S DESCRIPTIONS OF 



marked, posterior faint ; there is the impression of a small fold at right angles to the 

 hinge, placed just in advance of the beaks ; it is shown in the figure. A cast. 



Locality and position. — In Burlington Co., N. J., with the above. Collection of 

 the Academy. 



PECTEN, Bandelet. 



P. Burlingtonensis. PI. 48, fig. 26. Shell discoidal, as broad as high, marked 

 by numerous, irregular, concentric folds; ears nearly equal. A very fine cast. 



Locality and position. — "Brown sand," Burlington Co., N. J. Collection of the 

 Academy. 



Prof. Safford has kindly sent me, for examination, a series of cretaceous fossils, 

 collected by himself in connection with the geological survey of Tennessee. I have 

 been able to identify but two new species, Volutilithes Saffordi and Cardium abrwptum, 

 nobis. The most interesting specimens besides these are two, a whole valve and part 

 of another of Trigonia thoracica, S. G. M. These specimens are perfect in their 

 markings, and show some important characters not heretofore published, and prove 

 that it is not the same as T. alosformis, Sow., as Dr. Morton thought after having 

 published it. I shall thus characterize it : — 



Trigonia thoracica, S. G. M. PI. 47, fig. 10. 



T. alasformis, Sow. sp., S. G. M., Jour. Acad., 1st series, Vol. 8. Inequilateral, 

 truncated posteriorly, alated ; obliquely ribbed, the most anterior ribs almost parallel 

 with the lunule ; ribs about seventeen, compressed laterally, nodulose except near 

 the origin, where they are entire and sharp ; edge deeply serrate, each process corres- 

 ponding to one of the ribs ; anterior end slightly truncated obliquely; lunule marked 

 by a series of finely nodulated ribs, which point posteriorly ; surface between the ribs 

 marked by delicate lines of growth. 



Locality and position. — " Ripley group," Tenn. This fossil has been also found in 

 the Ripley group in Alabama, at Eufaula, Barbour Co., in the white limestone, Prairie 

 Bluff, Alabama; and in the marls of New Jersey. 



Remarks. — This beautiful species cannot be confounded with T. alaformis if we 

 examine the relations of the ribs. In our species, except for the swell of the shell, 

 they are straight. In the figure in Sowerby's Mineral Conchology the ribs are sinuous, 

 twenty-six in number, thicker and not so nodulose. They are all nearly at the same 

 angle with the lunule, which is nearly twice the width of that of T. thoracica. In 

 this the most anterior ribs form a very acute angle with the lunule, and the ribs 

 become more and more faint until the last is thread-like and hardly visible, while in 

 the former species they are thick and robust to the extremity of the shell. An 

 important difference is visible in the shape ; the beak is proportionally smaller and 



