NO. 7 NEW TOOTHED CETACEAN FROM SOUTH CAROLINA 5 



23.2 mm. in advance of the maxillary notch. The greatest vertical 

 depth of the supraorbital process of the left frontal is 12.5 mm., and 

 the greatest length is 61 mm. 



All of the braincase posterior to the presphenoid is missing. The 

 side of the presphenoid is visible from this view. Of the parietals 

 practically nothing remains except in the temporal fossa. Here a 

 portion of the lateral wing which overspreads the frontal and extends 

 forward to the posterior rim of the supraorbital process can be traced. 

 Below the supraorbital process and between the vomer and the arched 

 palatine is the exposed nasal passage. 



Ventral view. — The most striking feature of the ventral aspect 

 (pi. 2) is the relatively large size of the palatine bones. Anteriorly 

 they extend forward beyond the maxillary notches, but in Archaeo- 

 delphis they terminate slightly posterior to them. The palatine region 

 of the Agorophiiis skull was not figured. In contrast to Archaeo- 

 delphis, the alveolus of the last molar in Xenorophus is not situated 

 in advance of the anterior margin of the palatine. Externally the 

 palatine contributes the lower and outer margins for the infraorbital 

 foramen. Each palatine attains its maximum horizontal expansion 

 in a line with the inferior margin of the jugal. The emargination of 

 the anterior end of each palatine is quite noticeable and rather irregu- 

 lar. Together they are almost as broad as the space between the 

 tooth rows, but they were not in contact mesially. 



The vomer first appears as a splint-like bone inserted between the 

 maxillae, commencing near the anterior margin of the alveoli for 

 the first two-rooted teeth, and disappearing at the level of the last 

 tooth. It appears again between the palatines at the level of the 

 infraorbital foramina and extends backward beyond their posterior 

 margins. The vomer is very thin and crest-like between the posterior 

 margins of the palatines but from there on abruptly diminishes in 

 height and increases in width, and finally sheathes the entire ventral 

 face of the presphenoid. It is deepest at the nasal passages. 



Between the anterior margins of the palatines and the first two- 

 rooted teeth, the maxillae are separated from each other by the vomer. 

 In front of this bone the premaxillae form a wedge which increases in 

 width anteriorly. The ventral surfaces of the maxillae are rather flat 

 between the rows of two-rooted .teeth, and are marked by shallow 

 longitudinal grooves. The base of the rostrum is characterized by a 

 well-marked constriction which commences at the postero-external 

 angles of the alveoli for the next to the last molars. Posteriorly, 

 the maxillae are overspread by the palatines. 



