OF THE OPUIDIAXS IN GENEKAL. 25 



to the ophidians ; the last traces appear in the Anguis 

 and Acontias, and totally disappear in the Amphisbnena 

 and the Typhlops. The simple suspensory bones of the 

 jaw, the tympanites of serpents, replaced in most of the 

 Saurians by two pieces, are found in the Acontias, although 

 they are wanting in the Amphisbsena and the Typhlops. 



The whole bones of the cranium would perhaps furnish 

 better marks of distinction between the two allied orders, 

 if some species of the family of T}T^)hlops, the Uropeltis, did 

 not, in this respect, approach the Ophidians. It is well, 

 however, to obtain an idea of the principal differences which 

 distinguish the skulls of Saurians from those of Serpents. 

 The bones of the face of the latter never form an immove- 

 able mass, perforated by the nostrils, and composed of 

 pieces let into each other ; as we observe in Saurians. In 

 Ophidians, the intermaxillary bone of a compressed trian- 

 gular form, is always free, mobile, and never united to the 

 maxillaries by means of sutures ; the latter bones, when 

 they are intimately united to the anterior frontals, present 

 only a narrow attachment, and always possess some degree 

 of mobility ; and the lateral edges of the nasal bones are 

 always free through their whole extent. The Pterygoids 

 constantly present themselves in the form of thin, slender 

 bones, rather broad, and joined to the cranium by liga- 

 ments, which readily yield to the movements, more or less 

 extensive, which these parts are capable of performing. 

 No Ophidian has a mouth armed with large conical teeth, 

 perpendicularly implanted ; the organs in serpents, on the 

 contrary, resemble hooks bent backwards, with sharp points ; 

 besides, serpents, Avith the single exception of the Oligodon, 

 have the palate furnished with teeth like those of the jaws, 

 whilst we find among the Saurians only traces of palatal 

 teeth, in the form of minute irregular asperities. 



It may be seen, from all we have said on the structure 

 of Ophidians, that these reptiles are especially remarkable 

 for their mode of locomotion, and the manner of swallow- 

 ing their prey. These are the circumstances which modify 

 their whole structure : the first determines the general form 

 of their bodies ; the second, that of their internal parts. 

 We observe, on examining the general position of their in- 



c 



