974 THE OSTEOLOGY AND MYOLOGY OF THE DEATH ADDER, 



not the true ones, but that the fangs are erected through the 

 action of special muscles on the pterygoid bones. The observations 

 of Weir Mitchell on this point entirely agree with our own, 

 namely, that the mandible may be depressed and the mouth 

 opened to any width without necessitating the erection of the 

 fangs. He has farther shown that by stimulating the special 

 muscles attached to the pterygoid bones, erection of the fangs took 

 place. Observations made on the dry skull are misleading, and 

 tend toward the theory advocated by Huxley. 



We will now follow the snake through those complex move_ 

 ments which take place when a prey is struck. A snake 

 approaches its prey with movements which are almost imper- 

 ceptible, since they are made of numerous small motions which 

 are rendered possible by the great differentiation which has taken 

 .place in its body. When it deems that it is sufficiently close to 

 its prey it begias the following movements : — the head and the 

 anterior vertebrae are raised somewhat from the ground, and the 

 head is brought back so that the exoccipitals are placed in appo- 

 sition with the atlas, which in turn is jammed against the axis. 

 This is brought about by the contraction of the dorsal muscles, 

 which are produced on to the skull. At the same time some of 

 the anterior vertebrae are so bent that they form a slight bow 

 with the convexity forward. 



While this has been taking place the digastric contracts, and 

 pulling on the posterior extremity of the mandible, rotation takes 

 place round the quadrato-mandibular joint, and the anterior 

 portion of the mandible is depressed. The digastric is aided in 

 this action by the depressor mandibulse, and the costo-mandibulee 

 and mylohyoid attached to the inferior and anterior portion of 

 the mandible. Along with the opening of the mouth the fangs 

 are erected by the spheno-pterygoid and the parieto-pterygoid ; 

 the one acting above, the other below, draw forward the pterygoid, 

 which leads to the rotation of the maxilla and prefrontal, since 

 the transpalatine attached to the pterygoid shares with this latter 

 bone its forward motion, and consequently being also attached to 



