348 



CLASS REPTILIA. 



Comparatively few fossil forms are known, and these but 

 imperfectly. The oldest, but incompletely known, form is 

 Macellodon from the Upper Jurassic (Purbeck Beds). In the 

 Lower Eocene they are more numerous, belonging to the 

 Varanidae {Thinosaurus), Anguidae {Glyptosaurus, etc.), 



FlO. 191. — Urinogenital organs of Lacerta agilis (after C. Heider). a, of the male, 6 of the 

 female. CI cloaca ; H testis ; Bb urinary bladder ; Md rectum (cut). N kidney ; 

 Nh epididymis ; Ov ovary ; P vestige of wolffian body ; Pe penes ; Sd femoral glands ; 

 SP pores of femoral glands ; T oviduct (mullerian) or its vestige in the male ; Vd vas 

 deferens. 



Iguanidae [Iguanavus) and Chamaeleontidae. The lacertilian 

 fossils of the Miocene belong largely to existing genera. There 

 are about 1800 living species. 



Sub-order 1. LACTERTILIA VERA. The nasal bones enter 

 the border of the nasal apertures, and the pterygoid is in contact 



