KEPTILIA. 143 



EEPTILIA, 



OPHIDIA. Cold-blooded vertebrates having palatine bone united with 

 pterygoid bone only. Continuity of parietal and sphenoid bones complete. 

 Riimi of lower jaw united by ligament. Eyes with simple epidermic eyelids. 

 (Cope.) 



Prominent Anatomical Features. Limbless ; bodies of vertebrae articu- 

 lated by ball-and-socket joints. Progression effected by muscular action 

 upon the abdominal scales and ribs. 



Disposition of internal organs. 



The tongue exsertile, generally bifid. 



Solenoglypha. Superior maxillary short, united to prefrontal. Tympanic 

 bone elongated. Fangs without external canal. Pupils elliptical. Occipital 

 region scaly. (Cope.) 



(L) Crotalidae. Erectile poison fangs in front. Few teeth in upper jaw. 

 A deep pit between eye and nostril. Head scaly. 



Caudisona. Upper surface of head covered with small plates, scale-like, 

 with a few larger ones in front. The tail is terminated by a well-developed 

 rattle. Subcaudul scutella? entire. Temporal and labial shields small and 

 convex. 



C. horrida (rattlesnake), Linn. Head angular. Scales between the su- 

 perciliaries small, numerous, uniform. Plates above snout, 2 anterior frontal 

 and 5 post frontal. Suborbital chain continuous, of large scales. Two rows 

 between this and labials. Labials 12-14 above, 5th largest; 13-15 below. 

 Scales on the back 23-25, all carinated ; carination on outer row obsolete. Tail 

 black. Above sulphur-brown, with two rows of confluent brown lozenges. 

 Light line from superciliary to angle of rnouth. Behind this a dark patch. 

 Rattle acuminate. 



Habitat. North America, warm rocky exposures. 



Other Species. C. durissa (Eastern rattlesnake). 



C. confluenta. Western. 



C. lucifer. California. 



C. atrox. Texas. 



Crotalus, Linn. Upper surface of the head covered with nine large plates. 

 The tail terminates in a rattle, generally smaller than in Caudisona. Sub- 

 caudal scutella entire, except a few at the end of the tail, which are bifid. 



C. miliaris, Hall Twenty-two or twenty-three dorsal rows of scales, all 

 of which are carinated, the lateral and first rows but slightly; a vertebral 

 brownish-red line ; seven series of blotches, one dorsal and three lateral, on 

 each side, the uppermost of which is obsolete and the lowest subject to 

 irregularities. Vertical plates subcordiform, occipital oblong and elongated. 

 A narrow white line commences at the lowest point of the orbit and passes 

 obliquely backward to angle of mouth. 



Habitat. Southern States. 



