50 INVERTEBRATE ZOOLOGY. 



Division II. AMNIOTA Embryo furnished with amnjon and al- 



lantois. Mesonephros and its duct pos- 

 sess an excretory function only in the 

 embryo, being replaced in adult life by 

 the definite kidney {vietanephros). The 

 mesonephros then disappears, except cer- 

 tain portions, which are utilized by the 

 reproductive system. 



Class IV. Reptilia Integument covered with scales, horns, 



and other structures of epidermic forma- 

 tion. Glands confined to a definite local- 

 ity (femoral glands of lizards) or want- 

 ing. Gills never developed, embryonal 

 gill-arches modified to subserve other 

 functions. A single occipital condyle. 



Sub-class I. Plagiotremata Cloaca! opening transverse, behind which, 



in the male, are paired organs of copula- 

 tion. Body uniformly covered by deli- 

 cate scales, which are cast oif yearly 

 often as a single piece. Habits terres- 

 trial and arboreal. Quadratum mova- 

 bly articulated with skull. 



Order 1. Lacertilia Four well-developed limbs in the tj'pical 



gano, and sternum or shoiilder girdle 

 present in forms with reduction of limbs. 



Sub-order 1. Fissilinguia Tongue long and slender, extensile, 



forked at the end. -^ Lacerta. 



Sub-order 2. Brevilinguia Tongue short and thick, thin and notched 



at tip. Limbs sometimes fail. -^ Anguis. 



Sub-order 3. Crassilinguia Tongue short and thick, rounded at tip, 



not extensile, if Iguana, Gecko. 



Sub-order 4. VermiUnguia Tongue very long, vermiform, thickened 



at tip. if Cliaineleo. 



