ZOOLOGY REPTILKS. 17 



VENENOSI. 

 FAMILY II. 



CROTALIDJ^. 



Char. 1. The head is generally large ; the superior maxillary boues are small, aad attached 

 to ligaments to a long pedicle, analogous to the external pterygoid apophysis. 



Char. 2. The upper jawbones are destitute of teeth, but are armed with sharp pointed, per- 

 vious, moveable fangs, through which the poisonous fluid flows. These fangs are sometimes 

 only grooved, at others there is a complete canal opening near their extremity, but in all 

 instances these channels communicate with the excretory ducts of the gland. The fangs, when 

 not erect, are concealed by a fold in the gum, from which they can be raised at the will of the 

 animal. Behind these are the germs or rudiments of several other fangs, destined to become 

 developed and to replace the original, should these be destroyed by accident, as not unfrequently 

 happens. 



Char. 3. The palate bones are armed with two rows of small, hard, solid and fixed teeth. 



Char. 4. The gland that secrets the poison is situated near the eye, under the temporal 

 muscle, so as to be compressed by its contraction. The poison varies in intensity, perhaps in 

 the different genera, but more so according to the state of the animal. It is most active in the 

 healthy snake in the summer season, when it has been long retained, when the animal is greatly 

 irritated, &c., &c. To be deadly, however, it must be introduced into the circulation, for it 

 can be taken into the stomach with impunity. 



Char. 5. These serjjents are all viviparous ; or the egg is retained in the female until it is 

 hatched, and the young animal is then expelled alive. — {Holbrook.) 



CttOTALUS, Linnteus. 

 CROTALUS CERASTES, Nob. 



Char. — Head covered with polygonal tubercles, larger in front, the latter in three rows ; two 

 small quadrangular plates, (anterior nasals,) one on each side, between the nostril and the 

 vertical rostral ; two quadrangular supero-nasals ; external border of supraciliary plates devel- 

 oped, BO as to present two horn-like, or, rather, triangular, processes, one on each side of the 

 head ; they measure, each, one line in height by two in breadth at the base ; from twelve to 

 fourteen supralabials on each side, the fifth the largest ; twelve inferior labials ; three rows of 

 scales between the eye and upper labials ; pits between the eyes and nostrils large ; twenty rows 

 of carinated scales, the inferior rows, near the abdomen, smooth ; body slender, much com- 

 pressed ; tail very short, with three or four rattles. 



Coloration. — Head, ash color above, a black irregularly margined band extending from the 

 posterior border of the orbit to within a line of the occiput ; a series of 41 transverse brownish 

 bands, yellow in the centre, along the back ; general color of animal above, light-yellow ; sev- 

 eral transverse bands upon the tail ; under surface, light-yellow, slightly clouded with spots 

 near the external margin of the abdomen ; abdominal scuta 146 ; two rows of post-abdominal 

 scutell. ; 14 single caudal scuta ; three inferior rows bifid. 

 3S 



