274 



REPTILIA. 



THE SECOND FAMILY OF THE SAURIANS,— 

 The Lizards, — 

 Is distinguished by its slender, extensible, and forked tongue, as in the Snakes ; by its lengthened body 

 and rapid gait ; the feet have each five toes furnished with claws, which are separate and unequal, 

 more particularly those behind ; their scales, under the belly and around the tail, are disposed in 

 parallel transverse bands ; their tympanum, which is on the upper part of the head, is membranous 

 and shallow ; a production of the skin, split longitudinally, and which closes by a sphincter, protects 

 the eye, beneath the front angle of which is a vestige of a third eyelid ; their false ribs do not form a 

 complete circle ; the males have a double penis ; and the anus is a transverse aperture. 



The species are very numerous and much varied, and we subdivide them into two great genera. 



The Monitors (recently termed, by a singular mistake, Tupinamhis), — 

 Are the largest of the whole tribe ; they have teeth in both jaws, but none on the palate, and the 

 greater number have the tail laterally compressed, in adaptation to aquatic habits. Frequenting the 

 vicinity of the haunts of Crocodiles and Alligators, it is said that they give warning, by a whistling 

 sound, of the approach of those dangerous reptiles, and hence, probably, their names of Sauvegarde 

 and Monitor, though this is not quite certain. 



They divide into two distinct groups. The first, or that of 



The Monitors, properly so called, — 

 Are known by their numerous small scales upon the head and limbs, the belly, and around the tail, 

 which latter has a keel above, composed of a double range of projecting scales. Their thighs do not 

 exhibit that range of pores found in most other Saurians. All are from the ancient continent. 



Two species, in Egypt, have been considered the types of separate subdivisions ; the Nilotic M. (Lac. nilotica, 

 Lin.), of Varanus, and the Ground M. (L. scincus, Merrem), of Psammosaurus, both of Fitzinger. Africa and India 

 produce many more, with sharper teeth and still more compressed tail. 



The other group of Monitors has angular plates upon the head, and great rectangular scales upon 

 the belly and around the tail. The skin of their throat is invested with small scales, and forms two trans- 

 verse folds. They have a range of pores on the inside of each thigh. Two subdivisions are required. 

 The first, or that of 



The Dragonets (Crocodilurus, Spix ; Ada, Gray), — 

 Is distinguished by caudal crests, like those of the Crocodiles, formed of raised scales ; their tail is 

 compressed. Such is 



The Great D. of Guiana (M. crocodllinus), Merr.), which attains a length of six feet, and is eaten. There are 

 various others in the hot regions of America. 



The Restricted Monitors {Monitor, Fitzinger), — 

 Have no keeled scales either on the back or tail ; their teeth are denticulated, but with age the hind- 

 most become rounded. 



Some, more particularly termed Sauvegardes, have the tail more or less compressed, and the belly scales longer 

 than broad ; they frequent the borders of water. One, in Brazil and Guiana, attains to six feet in length. It runs 

 swiftly on the ground, and takes to the water when pursued, into which it plunges, but does not swim ; it devours 

 all sorts of insects, reptiles, the eggs of poultry, &c, and nestles in holes winch it burrows in the sand. Its flesh 

 and eggs are eaten. 



Others, termed Amceva, merely differ in having a round tail, covered, as is also the belly, with transverse ranges 

 of keeled scales, which on the belly are broader than long. They are American animals, which resemble our Lizards 

 extremely, but, besides wanting molar teeth, the greater number have no collar, and all have minute scales on the 

 throat; their head, also, is more pyramidal than in the Lizards, and they have no bony plate over the orbit. 



The Lizards, properly so called, — 

 Form the second great genus of this tribe. They have the back portion of the palate armed with two 

 ranges of teeth, and are otherwise distinguished from the preceding animals by a collar round the 

 neck, which is formed by a transverse range of broad scales, separated from those of the belly by a 

 sDace covered with small ones like those of the throat, and also by a part of the bones of the skull 

 advancing over the temples and orbits, so that the -"vhole head is defended by a bony casque. 



The species are very numerous, and many are found in Europe [though two only in this country, L. agilis, which 

 is comparatively rare, and L. vivipara, which, unlike the other, is ovoviviperous, as in the Vipers, and extremely 



