366 



REPORT OF NATION A I. MUSEUM, 1893. 



there are similar fangs, but much larger, and difiering from those of 

 the Ehip^ by being folded up toward the palate, somewhat like the 

 blades of a jackknife when not in use. This must not be understood 

 to mean that the fangs themselves are movable; on the contrary, the 



/^ 



/ \ U-^4f 



Fig. 11. . 



SKULL OF RATTLESNAKE, FKUM ABOVE. 



(Alter Jan.) 



iig-. v:. 



SKCLL OF EATTLESNAKE, FHO.M rilUE. 

 (After Jan.) 



viper's faugs are as solidly fixed iu their sockets as are those of the 

 Elaps, but while iu the latter (see fig. 3) the maxillary bones, into which 

 the fangs are fastened, are elongated and horizontal, as in the harmless 

 snakes (see fig. 4), in the Crotalids they are extremely shortened and 



higher than long, so as to appear iu a 

 vertical position. In the former the 

 fangs are consequently inserted nearly 

 at right angles, like the pickax on its 

 handle, Avhile in the latter the fang 

 more nearly represents the blade, and 

 the jawbone the handleof aknile, and 

 it is the jawbone which is movable in 

 the vertical i)lane, notthe fang alone. 

 In order fully to understand the 

 mechanism iu question, it is necessary 

 to remember that the bones of the head 

 of nearly all snakes (figs. 11-13) are so 

 loosely joined together as to allow a 

 most extraordinary amount of move- 

 ment and distention. Elastic ligaments connect bones which in other 

 animals are either grown solidly together or articulated by means of 

 close joints, hence a snake is capable of swallowing a prey many times 

 as thick as the snake's own body. 



As Jilready noted, the upper jawbones (maxillaries) are situated ver- 

 tically, one on each side of the anterior portion of the mouth, the hollow 

 fang being fastened into tlie lower end of the boue. On the outer face 



Fiff. Vi. 



bKVLL OF RATTLESr.'AKE, FRO.M BELOW. 

 (After Jan. ) 



