io8 



AMPHIBIA AND PISCES OF THE PERMIAN OF NORTH AMERICA 



A. 

 B. 

 C. 

 D. 



37. — T. insignis. 



Outline of base of skull. No. 4565 Am. Mus. X !• 

 Cross-section of occipital condyle of same. 

 Outline of base of skull. No. 4557 Am. Mus. X f . 

 Cross-section of occipital condyle of same. 



the type, the sides of the posterior part of the parasphenoid are much more 

 sharply cut out and the whole region is narrowed; the section of the occipital 

 condyle is broadly heart-shaped. In No. 4557 the same region is much 

 broader, and the section of the occipital condyle is a wide oval. It is pos- 

 sible that these should be 

 reckoned as distinct species, 

 but it seems best to wait for 

 more evidence. 



It is impossible to make 

 out the sutures between the 

 bones in the anterior part 

 of the palate. The internal 

 nares are far forward, and 

 the palatine and prevomer- 

 ine regions are covered with 

 small teeth; there are no 

 tusks visible. 

 The lower jaws are widely separated posteriorly, due to the width of the 

 skull; they curve forward and inward and meet in a narrow symphysis. The 

 outer surface of the jaw is covered with a beautiful sculpture, which is par- 

 ticularly heavy over the posterior surface and radiates from a point near the 

 lower edge (plate 12, fig. 4). The articular surface is as described by Cope. 

 Just anterior to the articular region, on the inner side, there is a wide open- 

 ing into the Meckelian cavity; there seem to be no anterior openings of 

 this cavity, but two small foramina penetrate the jaw, one just below the 

 articular surface near the posterior end, and another directly below the 

 anterior end of the Meckelian opening. The sutures which have been made 

 out are shown in fig. 38. There is a single series of irregular teeth on the 

 edge of the jaw, except just anterior to the opening of the Meckelian cavity, 

 where there is an oval patch of small, sharp teeth, about 3 cm. long, inside 

 the regular series and separated from it by a deep groove. The anterior 

 tooth is somewhat larger than the others. A large pit on the inner surface, 

 about 2 cm. from the anterior end, indicates the presence of a tusk on the 

 palatine. 



Fig. 38. — T. insignis. Inner view of right lower jaw. No. 4714 Am. Mus. X f . 



The vertebrcs are in general as described by Cope. The prominent char- 

 acteristic is the divided or weakly united condition of the two halves of 

 the neural spine. 



The first vertebra has a form similar to that of Eryops; the neural arch 

 is divided into two halves, each terminating in a sharp spine. These spines 

 are incHned backward and lie on either side of the enlarged spine of the 

 second vertebrae. A small, button-like process lies on the anterior surface 

 of each half just opposite the neural canal, and probably served for con- 



