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APPENDIX. 



JBeing a notice and description of the Organic Remains embraced 

 in the preceding paper ; by Samuel George Morton, M.D. 



Note. — I have had a good deal of hesitation in naming the Spir- 

 ifers and Producti of this paper, because many species have been 

 already described by naturalists, to whose works I could not gain 

 access in time, to avail myself of them ; such names are, therefore, 

 to be considered provisional only. The Uniones and Ammonites, 

 on the other hand, are decidedly new. With respect to the veget- 

 able remains, I have compared them with the figures given by Stern- 

 berg, Brongniart, and Lindley, but in many instances without suc- 

 cess. This department will require much more time, and a diligent 

 comparison of specimens. 



PLATE I. 



TJnio* pttrosus. (S. G. M.) Fig. 17. Shell subovate, compres- 

 sed ; disks somewhat flattened, cuneiform inferiorly ; posterior side 

 subcuneate. 



Unio tumulatus. (S. G. M.) Fig. 18 and 21. Shell subovate, 

 compressed ; posterior end cuneiform ; umbonial slope angular; mar- 

 gin swelling anterior to the middle. 



Unio terrenus. (S. G. M.) Fig. 19. Shell elliptical, elongated ; 

 anterior end rather narrower than the posterior ; umbonial slope 

 rounded, indistinct. 



Unio saxulum. (S. G. M.) Fig. 20. Shell elliptical, elongated, 

 compressed ; posterior side cuneiform ; extremity acutely angular. 



Anodonta 1 abyssina. (S. G. M.) Fig. 22. Fig. 23, view of the 

 basal margin. Shell elliptical, ventricose ; beaks rather prominent, 

 pointed ; umbonial slope not prominent. 



Ammonites Hildrethi. (S. G. M.) Fig. 24. Smooth, ventricose, 

 with two or three volutions : sutures jugiform, crowded : diameter, 

 two inches and a half. 



This fossil is a silicious cast : it is one of the most remarkable spe- 

 cies I have ever seen, and I have much pleasure in giving it the 

 name of the intelligent author of the preceding paper. 



* In determining these species of Unio, I have availed myself of the superior 

 judgment of Mr. T. A. Conrad. 



