430 EXTINCT MAMMALIA OF NORTH AMERICA. 



cast of the specimen, represented in Dr. Gibbes' figure 4, the enamel is indicated to 

 be about the same depth as in the tooth about to be described. 



The crown is nearly a third wider than high at the middle, and has its borders 

 provided each with three denticles, of which the posterior are much the larger and 

 extend nearer the summit. The enamel is strongly wrinkled internallj^, less so ex- 

 ternally, but in some positions is nearly smooth. Dr. Gibbes describes and repre- 

 sents the enamel in the teeth of his Dorudon to be uniformly smooth. The fangs 

 united in the body of the tooth, but separated the greater part of their length, extend 

 nearly straight or slightly convergent from the crown. As in the other teeth they 

 are solid. 



The molar, represented in figure 5, from the back of the series, is a diminished 

 likeness of the corresponding tooth of Basilosaurus cetoides, represented in Prof Em- 

 mons' figure 3, plate II, of Vol. Ill, of the Amer. Jour, of Agriculture, and copied in 

 Miiller's work, " Ueber der Zeuglodonten," figure 5, plate XXIII. 



The crown is much broader than the length, and is thickest on a line with the 

 middle of its anterior narrower fang. The anterior border is acute, and impressed at 

 the sides, especially externally, but it presents no conspicuous denticle except a rudi- 

 mental one at the base. The posterior, longer, more sloping border forms, together 

 with the summit of the crown, a series of six denticles. The fangs project nearly 

 straight from the crown, and, as in the preceding teeth, are solid. 



The measurements of the teeth are as follow: 



Lcugth of crown, ...... 



Breadth of crown, . . . . . , . 



Thickness of crown, ...... 



Length of fangs, when entire, .... 



A specimen of a much mutilated premolar tooth, represented in figure 6, plate 

 XXIX, from the Ashley River, South Carolina, in its size and appearance looks as if 

 it might pertain to the same animal as the preceding. The specimen, loaned by Prof 

 Holmes, was probably derived from the eocene formation. 



The crown is compressed conical, slightly curved and defined by acute ridges, of 

 which the entire one behind presents, near the base, a clasping tubercle. When 

 perfect, it has measured about ten lines long. The enamel is wrinkled as in the 

 teeth above described. The fangs were connate through the greater part of their 

 length, and they are gibbous and solid. 



A cervical vertebra from the Washita River, Louisiana, originally referred to a 

 cetacean with the name o£ Poniogeneus jviscus, appears to agree nearly in size, form, 

 and construction with the cervicals described by Miiller as those of Zeuglodon hracliy- 

 spondylus. The specimen has the body three inches in breadth, with nearly the 



