72- 



instead of forming a canal, is laterally extended, in the manner of an 

 ear-like process. There is only one fold on the columella. This is, 

 undoubtedly, the largest uniiocular univalve shell that is known. 



Mr. J. C. Delametherie, Journal de Physique, &V. Tome LXV. Nov. 

 1807, says, "I have a gigantic fossil cerite, cerites gigas, Lam. which 

 Mr. Maclure, of the Philosophical Society of Philadelphia, found at 

 Grignon, in a mineralogical tour which we made there in the month of 

 July. It is the largest which is known. Its circumference, near the 

 mouth, is from twenty-two to twenty-three inches, or about seven inches 

 and a half in diameter. The thickness of the lip is about seven lines.^ 

 Its complete length should be about thirty inches ; but it is broken, and 

 the piece which I have is but about ten or twelve inches long." 



In addition to this statement of the learned author of La Theorie de la 

 Terre, I have the pleasure to state, that I am in possession of a nearly 

 corresponding specimen, a cast, which I purchased out of the Leverian 

 collection, and which in all probability was obtained from Grignon. It 

 is a lime-stone cast, in which six turns, with the mouth, is so well pre- 

 served, as decidedly to determine it to have derived its form from a shell 

 of this genus. This shell must have exceeded in size that of M. Dela- 

 metherie ; since, independent of the thickness of the shell, its greatest 

 circumference, near to the mouth, is nearly twenty-four inches ; its dia- 

 meter being, of course, about eight inches. This specimen is about 

 sixteen inches in length ; and its weight, there being no externally 

 adhering matrix, is full twenty-one pounds and a half. M. Delame- 

 therie concludes, from his fragment, which is from ten to twelve inches 

 in length, that the shell must have been thirty inches in length ; but I 

 think, from the proportions of rny fragment, which, being nearly six 

 inches longer than that of M. Delametherie, gives better grounds of 

 calculation, that he may have over calculated the original length of the 

 shell ; since I cannot believe that my specimen, if perfect, although larger 

 than his, would have attained more than twenty-eight inches. 



