42 A SYNOPSIS OF ANIMAL CLASSIFICATION. 



profusion of chitinous organs, often 

 of great complexity; embryo de- 

 veloped within an egg; a single 

 median occipital condyle. 



Class III. KEPTILU Integument covered with scales, 



horns, and other structures of epi- 

 dermic formation. Glands con- 

 fined to a definite locality (femoral 

 glands of lizards) or wanting. 



The Orders of living reptiles are conveniently arranged under the 

 the two groups of Plagiotremata and Hydrosauria, but if the fossil 

 Orders were included, this classification would require some amendment. 



Group I. PLAGIOTREMATA..Cloacal opening transverse, behind 



which, in the male, are paired 

 organs of copulation. Body uni- 

 formly covered by delicate scales, 

 which are cast off yearly, often as a 

 single piece. Habits mainly ter- 

 restrial and arboreal. Quadratum 

 movably articulated with skull (ex- 

 cept in Rhynchocephalia, v. infra). 



Order i. Lacertilia Four well-developed limbs in the 



typical forms, and sternum or 

 shoulder girdle present in forms in 

 which the limbs are reduced. 



Order 2. Ophidia Body very much attenuated, limbs 



wanting, no rudiment of shoul- 

 der girdle or sternum. A single 

 lung developed (right). Other 

 paired organs placed the one be- 

 hind the other. 



X Crotalus, Python. 



A single species of a very ancient type of lizard occurs in New 

 Zealand Sphenodon {Hatiend) punctata. The quadrate is immovable, 

 ventral ribs and abdominal sternum are present, the vertebrae are amphi- 

 ccelous. It is referred to the Order Rhynchocephalia. 



