244 



TRANSACTIONS OF THE 



DESCRIPTION OF SOME ORGANIC REMAINS CHARACTER- 

 IZING THE STRATA OF THE UPPER TRANSITION WHICH 

 COMPOSES MIDDLE TENNESSEE. By G. Troost, M. D. 



Hamites. 



The fossil under examination coincides in some re- 

 spects with the Hamites funatus, Brong., but its ribs are 

 not quite as oblique as represented in the figure given 

 in Descriptions Geologiques des Environs de Paris, 2d 

 edit., pi. 7, fig. 7. In this respect it is intermediate 

 between the H. rotundus, Sow., and the H. funatus ; but 

 its transversal section is in the form of an ellipsoid. In 

 our specimen the diameter of one of the extremities is 

 much larger than that of the other, which seems not to 

 be the case v/ith the one represented by Brongniart. In 

 only a few places of it has the shell been preserved, which 

 seems to have been very thin, so that the greatest part 

 of it miist be considered as a cast. 



I have not been able to learn what size those found 

 in Europe generally have, and cannot therefore say 

 whether our Hamites is uncommonly large, as I am rather 

 inclined to believe. If we can rely on the names, the H. 

 gigas, Sow., is a gigantic species; I am not acquainted 

 with its size, but the H. maximus of the same naturalist 

 must, no doubt, be the largest that Sowerby has observed. 

 I find it has 10 lines in diameter and 2 inches in length ; 

 ours has, from one extremity to the other, measuring out- 

 side, 19 1 inches, and both extremities are much mutila- 

 ted ; but one can form a more correct idea of its size by 

 stating that the circumference of its larger extremity is 

 10| inches. 



