SAURIA. 



279 



Some have a spiudle-shapc; and others, which are nearly cylindrical, and more or less elongated, resemble 

 Snakes, and more particularly the Orvets (Anguis), with which they have many internal points of rela- 

 tionship, and which thus grade from the family of Iguanas by an uninterrupted series of transitions. 

 Tor the rest, the tongue of this genus is fleshy, and but slightly extensible and notched ; and the jaws 

 are armed all round with small serrated teeth. The remainder of their conformation approximates 

 more or less to that of the Iguanas and Lizards, and all their toes are unguiculated and free. Certain 

 species have palatal teeth, and a dcntelated anterior border to the tympanum, while others (the Tiiiqua, 

 Gray) have no teeth to the palate. 



The Seps (Seps, Daud.) — 

 Merely differ from the Scinques by having the body still more elongated, almost like that of an Orvet, 

 and the feet still smaller, the fore and hind being also more separated from each other. Their lungs 

 begin to exhibit some irregularity. 



The Dipodes (Bipes, Lacep.; — 

 Compose a small genus, which only differs from Seps by the total absence of anterior limbs, merely re- 

 taining the scapulars and clavicles buried beneath the skin, and the hind feet alone being visible. There 

 is but one step from them to the Orvets. Some have a range of pores on each side of the anus, which 

 is not found in others. 



The Chalcides (Cfialcis, Daud.) — 

 Are very elongated and snake-like Lizards, like the Seps ; but their scales, instead of being disposed 

 tile-fashion, are rectangular, and form transversal bands on the tail, like those of ordinary Lizards. 



Some have a groove along- each side of the trunk, and the tympanum still very apparent. They approximate 

 the Cordyles, as the Seps do to the Scinques, and lead, in a variety of ways, to the Pseudopodes and Ophisaurs. 

 Others have a concealed tympanum, and conduct to the Chirotes, and thence to the Amphisbaenes. 



The Chirotes {Chirotes, Cut.) — 

 Resemble the last by their verticillated scales, and still more the Amphisbaenes, by the obtuse form of 

 the head; but are distinguished from the former by the absence of hind feet, and from the latter by 

 the existence of fore-feet. 



The only species (C. lumbricoides) inhabits .Mexico, and has all the internal organization of an Amphisbsne, with 

 femoral pores, and one great lung and the vestige of a second, as in most Ophidians. 



In fact, the genera which terminate this order of Saurians interpose in so many ways between the 

 ordinary Saurians and the genera placed at the head of the Ophidians, that many recent naturalists 

 object to separating the two orders, or at least establish one comprised of the Saurians in part, detaching 

 the Crocodiles, and another of the Ophidians pertaining to the family of Anguis; but among the fossils 

 of the ancient limestone formations are found two very extraordinary extinct genera, which, with the 

 head and trunk of a Saurian, have feet borne on short limbs, and composed of a multitude of little 

 articulations, which form in the aggregate a sort of fin or swimming-paw, analogous to those of Ceta- 

 ceans. The first of these genera, or that of 



The Icthyosauuus, — 

 Had a large head and short neck, enormous eyes, middle-sized tail, and elongated jaws armed with 

 conical teeth, insertetl in a groove. 

 Several species are found in England, France, and Germany, some of immense size. 



The other genus, or 



The Plesiosaurus, — 

 Had a small head, and extremely long serpent-like neck, composed of more cervical vertebra- than that 

 of any other known animal. Its tail was short, and its remains arc found in the same calcareous strata. 



These two genera, for a knowledge of which we arc principally indebted to the researches of Mesa 

 Home, Conybeare, Bnckland, &c, were inhabitants of the sea. They should form a verj distincl family, 

 but what is known of their osteology approaches more to that of the ordinary Saurians than the I 

 diles, with which Utter thej have been gratuitously associated by M. Rtringer, since neither their tongue 

 nor scales are known, which are the two most distinctive characteristics of the loricate [It has since 

 been ascertained that they were covered merely with skin, apparent!] as in the Batrachians ; and there is 

 reason to suspect that the Icthyosaur possessed a cartilaginoui dorsal tin, as in man] of the true Cetacea ] 



