MR. TUOMEY ON THE ZEUGLODON. 17 



Description. Occipital bone somewhat semicircular, transversely flat or slightly 

 concave, central portion thin; a crest-like ridge surrounds the superior portion termi- 

 nating in the suture with the temporal bone. Condyles two, articulating surfaces 

 lunate, and almost enclosing tlie foramen magnum. Foramen magnum oval ; trans- 

 verse diameter \h inches, vertical diameter 1 inch; transverse processes thick, 

 spreading, making the breadth of the base of the cranium equal to its diameter across 

 the zygomatic processes; jugular foramen \ inch in diameter; temporal bones small, 

 mastoid portion thick and strong but not prominent ; articulating cavities for con- 

 dyles of lower maxillae large, forming about 30° of a circle, inclining inwards and 

 backwards; maxillse thick and strong, vertical section triangular ; a cavity for nerves 

 and vessels runs within at the points of the roots of the teeth ; alveolar process thick ; 

 palatal bone strong, anteriorly emarginate and horizontal, posteriorly descending 

 below the alveolar process. 



Frontal bone and anterior portion of maxillae wanting ; walls of the nasal canal 

 smooth ; sutures squamous ; in the left maxilla one tooth remains, which is solid, spear- 

 shaped, edges coarsely serrate, exterior side flattened, interior side convex, agreeing 

 in this respect with the position of the teeth in the shark ; roots double, nearly paral- 

 lel, and inserted obliquely backwards; in the right maxilla are the alveolae for eight 

 teeth with double roots. In the solidity of the teeth and slight divergency of the 

 roots, this specimen agrees with the figures of Dr. Harlan and Prof. Emmons. 



This fossil is particularly interesting, as it removes every doubt, if any remain, of 

 the true character of the animal to which it belonged. The double occipital condyle 

 shows it to have been a mammal, while the squamous sutures and a symmetrical 

 form refer it to the Cetaceae. 



Dimensions. Length 14^ in.; greatest breadth 71 in. ; height 51 in.; length of 

 enameled portion of tooth i in. ; breadth I in. It was evidently a young individual. 

 (PI. v., fig. I and 2.) 



Geological position. The teeth described by Dr. Gibbes were found in the oldest of 

 the calcareous beds of the Eocene of South Carolina, which contain Carditaplanicosta, 

 (Sowerby,) and other well known Eocene fossils, together with Gryphcea mutahilis, 

 (Morton,) and Terehratula harlani, (Morton,) which are also common to the creta- 

 ceous formation. The fossil just described was found in upper beds of the Eocene ; 

 so that the Zeuglodon must have existed through the whole of the Eocene period ; a 

 period which, in South Carolina, was at least sufficiently long for the deposition of 

 three hundred feet of calcareous and sedimentary matter; a fact ascertained by 

 boring at Charleston. 



