10 DR. R. W. GIBBES ON THE 



Squahdon. I have not, however, seen these teeth, and know them only by Grate- 

 loup's brief descri ption. 



"With regard to Dorudon, I ha^ e a stronger suspicion that the large two-fanged, 

 compressed, serrated tooth which ^ou have transmitted to me, may prove to be an 

 anterior tooth of Zeuglodon {Basilosaurus, Harlan.) It would be desirable to deter- 

 mine accurately the modifications of form of the teeth in different parts of the jaws 

 of that very remarkable cetacean, and to this end I trust Mr. Koch's late discovery 

 in Alabama may contribute. 



" In the same box was the cast of the tooth of the Mosasaurus, and also two un- 

 coloured casts of simple tv.eth. One I take to be the canine of a bear. Were thess 

 found with the serrated teeth of Dorudon V 



Subsequently he says — 



"I had written Ihe foregoing before discovering in the pyramid of papers accu- 

 mulated during my absence, the packet of memoirs which accompanied the casts. I 

 observe therein that Dr. Gibbes has made the comparison of his Dorudon with Zeu- 

 glodon, and founds a di? tinction in the form of the jaw. With regard to the hoUow- 

 ness of the teeth of Dorudon, this might perhaps arise from the immaturity of the 

 individual which yielded the fossils. 



" The figure subjoined to Dr. Gibbes's most interesting paper reminded me of the 

 very old figure in " Scilla, de corporibus marinis; tab. XII. fig. 1, 1747," of serrated 

 teeth, which have been the subject of much speculation.* My last views of them 

 were that they were apparently premolars of the fossil Hippopotamus. f Dr. Gibbes's 

 discovery may prove them to belong to the very curious family of extinct cetacea of 

 which Basilosaurus is the type, and to which it is most probable that Dorudon 

 belongs. 



"The tooth like the canine of a bear" (PL II. fig. 1,:!:) "is not that which Dr. Gibbes 

 has figured," (PI IV., fig. 3;) " the figured tusk or canine belongs to a different genus 

 from the tooth I have likened to a bear's canine, and may probably be from the 

 lower jaw of Dorudon, as Dr. Gibbes supposes." 



The figured tusk alluded to by Prof. Owen, was subsequently proved to be from 

 the lower maxilla, for I fomid it inserted in a fragment of that bone. (PI. III., fig. 2.) 

 During an extensive exploration of the bed of green sand at the locality, with the 

 hope of turning up other portions of the skeleton, fragments of a lower maxilla con- 

 taining the then unfigured tusk were procured, with twelve caudal vertebrse. These 

 I was disposed to consider as belonging to another species, if not a new genus as sug- 

 gested by Prof. Owen, but a careful examination of Prof. Warren's specimens con- 

 vinces me that I must refer them to Z. cetoides. 



* I learn from M. Agassiz thai the tooth in the Univershy of Cambridge is the original which furnished the figure 

 given by Scilla. I have copied one of these teeth from Scilla. (PI. II., fig. 9.) 

 t Odontography, p. 564. 

 :j: This tooth was not figured in my original memoir, but a cast was sent to Prof. Owen. 



