LACKRTINIDA. 173 



nostrils, which open on the end of the muzzle by two small crescent-shaped 

 fissures closed by valves, communicate with the extremity of the hind part of 

 the mouth, by a narrow canal which traverses the palatine and sphenoidal 

 bones. 



The lower jaw being continued behind the cranium, the upper one appears 

 to be moveable, and has been so described by the ancients ; it only moves, 

 however, with the entire head. 



They have the power of closing the external ear by means of two fleshy lips, 

 and there are three lids to their eyes. 



The vertebrae of the neck rest on each other through the medium of small 

 false ribs, which renders all lateral motion difficult, and does not allow these 

 animals to deviate suddenly from their course; consequently it is easy to 

 escape from them by pursuing a zig-zag direction, or by running round them. 



Their eggs are as large and hard as those of a goose; the females keep 

 careful watch over them, and tenderly protect their young for some months. 

 They inhabit fresh water, are extremely ferocious and carnivorous, cannot 

 swallow under water, but drown their prey, and place it in some submerged 

 crevice of a rock, where they allow it to putrefy before they eat it. 



The species, which are more numerous than they were thought to be 

 previous to my observations, are referable to three distinct subgenera, viz. 

 GA VIALS, true CROCODILES, and ALLIGATORS. To the latter belongs 



Croc. Indus, Cuv. It inhabits the southern parts of North America, forces 

 itself into the mud in severe winters, and remains torpid. The female deposits 

 her eggs in alternate layers with beds of earth. 



FAMILY II. 



LACERTINIDA*. 



THIS family is distinguished by the tongue, which is thin, extensible, and 

 terminates in two threads, like that of the coluber and viper; the body is 

 elongated ; the gait rapid ; each foot has five toes, separate and unequal, the 

 hind ones particularly so, all armed with nails ; the scales on the belly and 

 round the tail are arranged in transverse and parallel bands ; the tympanum is 

 level with the head, or but slightly sunk and membranous. A production of 

 the skin with a longitudinal slit which is closed by a sphincter, protects the 

 eye, under whose anterior angle is the vestige of a third eye-lid ; the false ribs 

 do not form a complete circle. 



The species being very numerous and various, we subdivide them into two 

 great genera. 



* Lacerta, a Li/ard. 



