144 REPTILIA. 



passes into the Squamata (Lacertilia + Ophidia) in compara- 

 tively late geological times (fig. 91 E) ; while some of its 

 early divisions are generally believed to be related in an un- 

 determined way to the ancestry of the class Aves, which never 

 possesses the upper, though always the lower bar in question 

 (fig. 91 F). 



It is noteworthy that nearly all reptiles with well-formed 

 limbs whether adapted for habitual support of the body on 

 land, for flight, or for constant swimming flourished only 

 before mammals and birds became dominant ; the vast 

 majority of the survivors during the Tertiary period and in 

 the existing world being comparatively degenerate types. 



ORDER 1. ANOMODONTIA. 



The dominant group among the earliest reptiles in each 

 quarter of the globe where they have as yet been discovered, is 

 directly intermediate in skeletal characters between the highest 

 Labyrinthodonts (Mastodonsaurus and its allies) and the lowest 

 Mammals (Monotremata). Its members first received the 

 general name of ANOMODONTIA in allusion to the varied 

 modifications of the dentition, so unusual among reptiles. 

 They were afterwards named THEROMORPHA or THEROMORA, 

 in an equally general manner, in allusion to the many obvious 

 resemblances in their skeleton to that of the monotreme mam- 

 mals. Like most palseontological terms, both of these were 

 suggested prematurely before definition became possible, and 

 it seems preferable to retain the first until the osteology of 

 these reptiles is known with sufficient completeness to arrange 

 them in natural order. 



The Anomodonts, as now understood, are all land-reptiles 

 with limbs adapted for habitual support of the body. Some 

 'are of very massive build, while others must have been as agile 

 as a modern feline or canine Carnivore. The investing bones 

 of the temporal region of the skull either form a continuous 

 shield or contract into a single broad temporal arcade, which is 

 sometimes slightly pierced; and the firmly-fixed quadrate is 

 often much reduced in size. There is always a pineal foramen. 

 The teeth are placed in sockets, though sometimes also fused 



