191 



eludes our Common Rattler) is that the former has the top of the 

 head with about eight plates arranged in a rosette, and the rattle 

 is always very small, while the latter (or Crotalus) has the top of 

 the head covered with small scales instead of plates, and the 

 rattle is generally large. 



The Prairie Rattler is brown or black, with about seven rows of 

 deep blotches, about thirty-four such blotches in each row, and 

 each blotch with a yellow edge and a blackish shade toward the 

 outside and edged with yellow. From the pit to the neck there 

 is a yellow streak. Occasional specimens may be found which are 

 all black (melanic), as with the Hog-nosed Adder. The ventral 

 plates number one hundred and thirty-tive to one hundred and 

 fifty, and the length rarely exceeds thirty inches. 



This species of reptile is the one found mostly on the prairies from 

 Ohio to Minnesota and southward, and lives mostly in grassy 

 fields. It is rare in Pennsylvania, being found only in the western 

 part of the State. We have not collected nor seen a specimen from 

 Pennsylvania, although Dr. Atkinson, of the Carnegie Museum, 

 Pittsburg, Pa., published in his "Reptiles of Allegheny County," 

 records of the occurrence of this species. Thus it occurs only in 

 the extreme western part of the State, according to our present 

 knowledge of its distribution in this Commonwealth. There are 

 no published observations on its food or feeding habits, although 

 Dr. Stejneger, in his ^'Report on the Poisonous Snakes of North 

 America," quotes Dr. Taylor as saying that it feeds on mice and 

 other rodents. No doubt in grassy regions it takes the place of the 

 Common Rattle Snake and its food must be very similar, with 

 due variations for the difference in haunts, as this species lives 

 mostly in grassy fields, while the next is to be found mostly in 

 rocky places. Consequently a variation in food should be expected, 

 with more insects, particularly grasshoppers, taken by this species. 



No. 24. Crotalus horrldus (L.). Common Rattlesnake. Piatt s XL, XLI. 



There is no mistaking the Rattle Snakes, as they are tlje only 

 serpents with horn^^ beads or rattlers on their tails. The noise 

 which they produce is also characteristic, and every person who 

 once hears it will never forget it. It sounds very muqh like escap- 

 ing steam or like a mingling of steam escaping and the shrill song 

 of certain species of crickets or locusts. The noise is no doubt 

 made to frighten away intruders and thus preserve the store of 

 venom which may be necessary for saving the life of the serpent 

 on another occasion or for tfiking its food. This venom is secreteil 

 slowly, and after the snake strikes two or three times there is 

 generally not enough left to produce very serious results. Thus it 



