STRUCTURE OF OPHIDIANS. 53 



the SNAKES, or ANGUES, rfiiguina. They are easily distinguished 

 by the imbricate scales, which cover the body like those of 

 the Scincoidea; they also approximate the Saurians by the 

 presence of three eye-lids, organs that are not found in true 

 serpents. The tongue is fleshy, and but slightly extensile, and 

 the bony skull possesses the same conformation as that of the 

 Scinques; and we find beneath the skin of most of these animals, 

 vestiges of a pelvis and shoulder bones. On the other hand, they 

 resemble true serpents in the general form of the body, and in 

 the small size of their lungs. They are very mild animals, and, 

 when taken hold of, do not attempt to bite. Their mouth is 

 small, and armed with teeth like those of the Scincoidea ; they 

 feed on different insects and terrestrial mollusks, and entirely 

 conceal themselves in holes, and are torpid in winter. Their 

 tail, like that of lizards, breaks with the greatest facility, and 

 some Angues stiffen themselves so much when taken that the 

 body breaks, which singular circumstance has obtained for them 

 the name of Glass-snakes. The Common JLngue of Europe, 

 rfnguis fragilis, is about a foot long, and its tail, which is 

 obtuse, and like the rest of the body, is of the same length as the 

 latter. Its scales are smooth and shining ; it is blackish beneath, 

 and of a yellowish lead colour above, with three black bands, 

 which, as it advances in age, change to a series of points, and 

 finally disappear ; it has no external tympanum. It digs subter- 

 raneous galleries, and produces its young like vipers, in which 

 the eggs are hatched before they are laid. 



41. The TRUE SERPENTS, Serpentia, possess no internal 

 trace of anterior extremities : they have no vestige of sternum 

 or shoulder ; but many of them have, beneath the skin, rudi- 

 ments of posterior extremities, which sometimes show themselves 

 externally, in the form of a small hook. The skin is furnished 

 with scales, which, in general, are small, and imbricate above, 

 and in the form of broad quadrangular plates beneath : they 

 have no tympanum, and their eyes appear to be entirely without 

 lids ; for they are only covered by a sort of single and immove- 

 able veil, which is set in, like a watch-glass, in front of the orbit, 

 and which permits the passage of light. 



42. The vertebra and ribs, by themselves, form almost the 

 whole skeleton of serpents. Their number is very considerable ; 

 in the viper we count 198 vertebrae; in the Boa, 304; and in the 

 Ringed Snake, 316. The form of these bones is nearly the same 

 throughout the column, and their mode of articulation is very 



41. What kind of eye-lids have true Serpents? What are the general 

 characters of Serpents ? 



42. What bones are most numerous in the skeleton of Serpents ? 



