Class 4, Beptilia. 



41 r 



consists of several bones : of these the most anterior may be anchylosed 

 ■with its fellow of the other side, as in Ohelonia. The hyoid 



Fig. 335. lands Skullof a Lizard (Varanus). — 2and4o£a Cro co dile, dorsal and 

 ventral. C occipital condyle, Ch posterior nares, co columella, E Buatachian tube, Fr frontal, 

 Ju jug'al, 1 in 2 lachrymal (in 1 a membrane bone present in some forms), Mx maxiUa,, 

 Na nasal, 06 basi-, 01 ex-, Os supra-occipital, Pa parietal. Pal palatine, Pf postfrontal, 

 P)/ prefrontal, Pt pterygoid, Px premaxiUa. Q quadrate, Qj (and the lower Q in 1) quadrato- 

 jugal, Sp'o basisphenoid, Sq squamosal, Tr transverse bone, Vo vomer. — Alter Gegenbaur. 



apparatus, i.e., the visceral skeleton, with the exception of the first 



visceral arch (the quadrate, pterygoid, palatine and mandible) » 



consists, in the Chelonia and Lacertilia, 



of an unpaired portion, the body of the 



hyoid, corresponding to the basi- 



branchials of Pish, and two pairs of 



c o r n u a which represent the hyoid 



and the first gill-bar respectively ;* in 



Crocodiles and Snakes only a single 



pair of horns is present, in the latter 



group the whole apparatus is very 



poorly developed. 



The most impoi-tant bones of the 

 reptilian skull, besides those already 

 mentioned, are the following : the o c c i - 

 pitals, a supra-, basi-, and two 

 ex-ocoipitals, surrounding the foramen 

 magnum; the petrosal, in front of the 



Fig. 336. Hyoid of a Lizard, 

 c body of the hyoid (copula), ftr^ first. 

 giU bar. — After Walter. 



■ In some Lizards there are traces of two cornua representing the second gill-bar. 



