FOSSIL SQUALID^ OF THE UNITED STATES. 143 



distinct and uniform in the teeth of both jaws. In many fossil species there are 

 lateral denticles on both edges at the base of the cone, which assist in distinffuishino: 

 species, but ai-e not uniform characters. In the geological distribution of the species 

 of this genus, it is a remarkable fact that a large number are found fossil, while there 

 is but a single representative in the recent C. lamia ; and the reverse is the case with 

 Carcharias, which includes numerous recent species, and has but few fossils. 

 Agassiz mentions only one, and doubts of another. The genus Carcliarodon is not 

 found beyond the Tertiary, the oldest remains being found in the calcaire grossiere 

 (Eocene.) In Europe he mentions the Swiss molasse, (Miocene,) as prolific in this 

 genus, while in South Carolina I find the Eocene more largely productive of them. 

 I have received a few from the former localities, while I have them abundantly from 

 the Eocene. I learn from Professor Agassiz that Mr. Tuomey, who has collected 

 Squalidce in the Tertiary beds of Virginia, has found more specimens of Carcliarodon 

 in the Miocene. 



1. C. MEGALODON. Figs. 1 to 9. — The general form is equilateral, the anterior and 

 posterior edges differ somewhat in the upper and lateral teeth, in consequence of the 

 slope and obliquity backwards. The marginal indentations are uniform over the 

 whole contour of the edges. The enamel is thin but strong, and extends to the root 

 on the outer surface, while there is a large triangular space between them on the 

 inner. This space in large and old specimens is rough with longitudinal cracks or 

 superficial fissures. The thickness is very considerable, in which it differs from the 

 European co-species. The inner face is prominent and the outer flat, in some 

 depressed next the edges and elevated in the middle, giving an undulated 

 appearance. The root is very thick, forming one-third or more of the depth of the 

 tooth; it is concave on the lower surface between the basal extremities, which are 

 rounded or flattened and for the most part symmetrical. The osseous structure is 

 dense and compact, and frequently cracked with fissures. The enamel is also 

 usually striated with longitudinal cracks. 



Fig. 1 is a lower tooth, and fig. 2 an upper lateral one ; fig. 4 is of the variety 

 C. rectidens, and figs. 5 and 6 of C. siibauriculatus, both which Agassiz now refers 

 to this genus ; fig. 3 is probably a symphysial tooth ; figs. 7 and 8 are young teeth, 

 the last destitute of dentelures and probably from the extreme posterior portions of 

 the jaw ; fig. 9 resembles C. sulcidens, but intermediate specimens prove it to belong 

 to C. megalodon. I have various specimens from the Eocene of South Carolina, and 

 Miocene of Virginia and Maryland. The largest individual measures six and a half 

 inches in heisrht, and five inches across the extremities of the root. 



Professor Owen in his Odontography (p. 30) says : 



37 



