144 DR. GIBBES' MONOGRAPH OF THE 



" Fossil teeth, precisely corresponding in form with those of the Carcharodon, occur 

 abundantly in the tertiary formations of both the old and new continents ; some of 

 these teeth exhibit the extraordinary dimensions of six inches in length, and five 

 inches across the base. If, therefore, the proportions of these extinct Carcharodons 

 corresponded with those of the existing species, they must have equalled the great 

 mammiferous whales in size ; and, combining with the organization of the shark its 

 bold and insatiable character, they must have constituted the most terrific and 

 irresistible of the predaceous monsters of the ancient deep." 



*' In the United Service Museum there are preserved the jaws of a Carcharodon, of 

 which the upper one measures four feet and the lower one three feet eight inches, 

 following the curvature. The length of the largest tooth is two inches, the breadth 

 of its base one inch nine lines : the total length of the shark was thirty-seven feet." 



Mr. Charlesworth has given a good figure of C. megalodon in the Magazine of 

 Natural History, (Vol. i. 1834,) and considers it from the Miocene, and Agassiz views 

 it as proper to the Medial Tertiary. In the United States we must consider it as 

 common to both. 



There are several fine specimens in the Museum of the Medical College of the 

 State of South Carolina, at Charleston, from the Eocene, and others in the Academy 

 of Natural Sciences of Philadelphia, but their locality is not given. 



Professor Hitchcock, in his " Geology of Massachusetts," p. 431, has given a figure 

 of a tooth from the Eocene of Gay's Head, which is probably C. megalodon. 



In my autograph collection of distinguished men, I have the originals of the 



following letters, indicating that in 1806 Dr. William Reid, of Charleston, had 



forwarded to Mr. Jefferson specimens of C. megalodon, from the Eocene beds of 



Cooper river. I am indebted to J. Harleston Reid, Esq., for the specimens and the 



letters : 



"Charleston, S. C, February 11th, 1806. 



" Sir, — Observing you attentive to Natural Philosophy as well as to other branches 

 of science, I take occasion to present you with a fossil, which you may consider a 

 curiosity, and not unworthy of your contemplation. It was found on Ricehope Estate 

 on Cooper river, in forming a canal twenty feet under the surface of the earth, and 

 ten feet above the level of the river swamp. It lay with several others of similar 

 form, in a stratum of earth resembling decayed sea shells, two hundred feet distant 

 from the swamp. I likewise send you a broken one, lest your Excellency should 

 choose to direct a chemical analysis on it. From my experiments, they prove 

 dentous. The curious here have concluded these fossils to be the teeth of some 

 monster unknown at this day. 



" I remain with all due respect and the highest consideration, your Excellency's very 

 humble servant, William Reid." 



Thomas Jefferson, Esq. 



