636 EEPTILES AND AMPHIBIANS. 



the Snapping Turtle, preys upon frogs, fishes, and young ducks ; while 

 Trionyx ferox is said to feed upon fish and small aquatic reptiles. 



Serpents vary full as much as turtles in regard to food. For instance 

 Idopellig vernalis, the Green Snake, is insectivorous ; Diadephis punctatus 

 the Ring-necked Snake, eats worms, insects, and grubs ; Storeria dekayi, 

 the Little Brown Snake, has been found with the elytra of beetles in its 

 stomach ; Eutsenia sirtalis feeds upon frogs, toads, and small quadrupeds ; 

 Abastor erythrogrammm takes rats ; Bascanion flagelliforme, the Coach- 

 whip Snake, preys upon birds ; Boa Constrictors and Pythons swallow their 

 species ; Ancistrodon contortrix, the Copperhead, eats mice, Ranidse, and 

 small birds ; Pilyophis melanoleucus takes mice, rats, rabbits, and young 

 chickens ; Opkibolus triangulus uses frogs and toads ; Bascanion constrictor, 

 the Blue Racer, consumes frogs, small birds, and other snakes, having been 

 observed swallowing a dead Evtsenia ; while in the stomach of Tropidonotiis 

 sipedon, the Water Snake, I have found frogs and small fishes, and in 

 Opkibolus getulus, the Chain Snake, the remains of other serpents ; Crotalus 

 durissug, the Rattlesnake, is said to live upon insects, frogs, lizards, mice, 

 moles, young birds, and chickens. Toads are ordinarily believed to be 

 eaten by serpents. However, the writer's experience, having in vain 

 endeavored to feed them to Bascanion constrictor and Crotalophorus ter- 

 geminuB, leads him to believe that toads are rarely preyed upon by «nakes, 

 but that they are sometimes eaten by Eutsenia sirtalis and Opkibolus 

 triangulus is, it appears, beyond question. The former he has himself 

 seen in the act of swallowing a Bufo americanus. 



The fangs of the venomous serpents* are firmly soldered to the lower 

 side of the maxillary bone, which joins the lachrymal above by a 

 ginglymoid articulation. Posteriorly it is in contact with the external 

 pterygoid and palate bones. A muscle, the spheno- pterygoid, which has 

 no analogue in other animals, extends from the base of the cranium in 

 the middle line, backward and outward, to be inserted into the external 

 pterygoid, which by contraction it draws forward, pushing the maxillary 

 before it and causing the fangs to be erected. At the same time, other 

 muscles cause the mouth to be widely opened and the anterior portion 

 of the body to be thrown forward, downward, or backward toward the 

 object aimed at. If the enemy is missed, the venom may spirt several 

 feet, but if struck, another pair of muscles, the external pterygoid, which 

 run from the point of articulation of the lower jaw forwards, and are 

 spread out as a fascial layer over the gland, and inserted by two slips 



*For a fuller treatise upon Crotalus poiiOBing, its venom and antidotes, see the ex- 

 cellent article by Dr. S. Wier Mitchell, Smithsonian Cont., vol. xii, to which the author 

 is largely indebted for facts here given. 



