ANATOMY OF THE POISON APPARATUS. 



103 



means alone. Pennant is authority for the statement, which I have no 

 other proof of, that the land-tortoise "is an utter enemy to the rattle- 

 snake; will seize it below the neck, and by drawing its own head into its 

 shell becomes invulnerable. The snake entwines about the tortoise, but 

 is soon destroyed and left on the ground." There is a queer belief 

 among some of the negroes, by-the-way, that if a snake is killed by the 

 rattler, the blacksnake rubs against the body and brings it to life; hence 

 that species is called the " doctor-snake." 



However the crotalus may manoeuvre to get his victims within reach, 

 once there he has a weapon on whose certainty he has no fear of relying 

 — the poisoned fangs in his opened jaws. The anatomy of the head and 

 poison apparatus, and re- 

 searches upon the ven- «£• 

 om of the rattlesnake, 

 formed the subject of a 

 long series of experi- 

 ments, some years ago, 

 by Dr. S. Weir Mitchell, 

 of Philadelphia, which 

 resulted in the publica- 

 tion of an elaborate 

 memoir in the twelfth 

 volume of the " Smith- 

 sonian's Contributions to 

 Knowledge." To this memoir further researches have recently been 

 added. 



In repose and unmolested the snake sometimes lies at full length, 

 sometimes twisted up ; in confinement, where several are in the same 

 cage, it is very fond of entangling itself with its fellows. The instant it 



is alarmed, however, it throws 

 .,..£ its body into the familiar coil, 

 its tail protruding enough to 

 admit of its vibration, the for- 

 ward part of the body lying in 

 short curves across the mass of 

 coils, and the head held three 

 or four inches erect. In this 

 position a sudden and violent 

 contraction of the muscles upon 

 the convexity of the curves 



CRANIUM OF CROTALUS, WITH MUSCLES CONCERNED IN 

 THE VENOM STROKE. 

 a, a, venom gland ; 5, anterior temporal muscle ; c, posterior temporal 

 muscle; d, digastricns; e, posterior ligament of tbe sheath of the 

 gland ; /, vagina dentis, the fang slightly raised. (Mitchell.) 



BONES OF THE UPPER JAW. 



a, external pterygoid bone; b, internal pterygoid; c, pala- 

 tal ; d, superior maxillary ; e, lachrymal. (Mitchell.) 



