ANOMODONTIA. 145 



with the supporting bone. The posterior (internal) nares 

 occupy their primitive forward position on either side of the 

 vomers; and the development of a secondary palate never 

 advances further than that in cortain Chelonia. The most 

 characteristic feature in the pectoral arch consists in the pre- 

 sence of ossified epicoracoids (sometimes termed precoracoids) 

 as large as those in existing Monotremes ; while clavicles and 

 a T-shaped interclavicle are also well-developed. There is an 

 entepicondylar foramen in the humerus, and the delto-pectoral 

 crest is very prominent. The vertebral centra are more or less 

 biconcave, and the anterior ribs are completely or imperfectly 

 double-headed. ,The number of sacral vertebrae is variable, 

 and intercentra (hypocentra) are usually rudimentary or absent. 

 No abdominal ribs and very rare traces of dermal armour have 

 been observed. 



All known Anomodonts seem to be of Permian and Triassic 

 age. 



Sub-Order 1. Pariasauria. 



The nearest approach to the Labyrinthodonts is exhibited 

 by the PARIASAURIA, which have the head completely covered 

 by a bony roof. The constitution of this roof in the typical 

 genus Pariasaurus, however, is as yet uncertain ; and no 

 undoubted impressions of mucus-canals have hitherto been 

 observed, although the external bones in this animal are 

 sculptured like those in many Labyrinthodonts. The teeth 

 are conical or with a compressed, cuspidate crown ; while those 

 on the margin of the jaw are arranged in a more or less 

 uniform series. 



Pariasaurus (figs. 92, 93). This is an animal of massive build, with 

 short tail, and especially stout limbs. It is known from one almost 

 complete skeleton (fig. 92) nearly three metres in length, and from other 

 more incomplete specimens. The head is triangular in form, short, broad, 

 and depressed. The cranial roof is coarsely sculptured, but not orna- 

 mented with bosses ; and the sutures between its component elements 

 have not been clearly observed. There is a double narial opening in 

 front ; the small orbits are laterally -placed ; and there is a conspicuous 

 pineal foramen. The temporal fossa is open behind on each side ; and 

 the very large single occipital condyle exhibits a slight indent. The 

 w. 10 



