220 LACERTILIA. 



Fam, Ptychopleurae. The body is provided with two lateral folds of skin, 

 covered with small scales. These folds extend from the region of the ear" to 

 near the anus, and form the boundary between the dor?al and ventral surfaces. 

 Zonurus Cordylus Merr. = griseus Cuv., South Africa ; Pseudopus Pallasii, 

 Cuv., South-east Europe, and in lower Austria ; Pyrjopm (JBipcs) lepldopus 

 Lacep., New Holland (fig. 641) ; Chamasaura anguina Schn., Cape ; Ophisaurus 

 ventralis Daud., North America. 



Sub -order 5. Fissilinguia. Pleurodonta, with long and thin, pro- 

 trusible bifid tongue, usually with complete eyelids, and always with 

 exposed tympanic membrane. The scales of the trunk are small and 

 imbricated, those of the long tail mostly lozenge-shaped. 



Fam. Lacertidae. Mostly brightly coloured, very agile Lizards, with long 

 tail and head covered with scutes. The ventral surface is covered with usually 

 rhomboidal scales, arranged in oblique rows. Lacerta vivipara L., Germany 

 and South Europe, viviparous ; L. occllata Daud. ; L. viridis, green with 

 black spots in front, Dalrnatia ; L. af/ilis L. = stirpiiun Daud., common 

 Lizard ; L. muralis Merr., South Europe ; Heloderma horridum Wiegm., Mexico. 



Fam. Ameividae. Lizards of the New World whose head is covered with 

 scutes, as in the Lacertidce, while the abdomen is covered with rhomboidal 

 scutes, arranged in transverse rows. Tejus monitor Merr. = T. Tejuexin L., 

 Brazil, live in holes in the earth and in hollow trunks of trees. Feed on Mice, 

 Insects, and Worms, and are, including the long tail, four or five feet long. 

 They are hunted and eaten. Ameiva vulgaris Licht., West Indies. 



Fam. Monitor idse. Elongated Lizards of large size, without femoral pores. 

 The crown of the head, the back and the abdomen, are covered with small 

 plate-like scales. The separation of the ventricles of the heart is the most 

 complete in the whole order. Psammosaurus scincus Merr. = Varaims arenarius 

 Dum. Bibr., Egypt ; the Land Crocodile of Herodotus ; Monitor niloticus Hassl., 

 eats the eggs of the Crocodile. 



The Proterosauria and Thecodontia are fossil groups of Saurians. 

 The former represent the oldest Lizards, and are distinguished by the 

 possession of biconcave vertebral bodies and bifid spinous processes. 

 They are found in the Kupferschiefer. The Thecodontia, also with 

 biconcave vertebrae, possessed compressed teeth wedged into alveoli, 

 with their crowns covered with finely serrated striae ; they belonged 

 to the Triassic period. 



The fossil Dinosauria must be mentioned as a special order of 

 Reptiles. These were the colossal terrestrial inhabitants of the Jura, '' 

 Weald, and lower chalk ; in several features of their structure they 

 recall Mammals, especially the Pachydermata. 



Other orders of fossil Saurians, as the Ornithoscelida, present 

 modifications which point in various ways to the organisation of 

 birds. Characterised by the prseacetabular extension of the ilium 

 and the downward direction of the elongated pubis and ischium, they 

 possessed, at least in the group which includes the Jurassic genus 



