234 REPTILES OF MASSACHUSETTS. 



above the two lateral plates, two others are situated ; the first, 

 meeting the snout anteriorly,, and the second, extending some 

 distance beyond the nostrils behind. At the anterior angle of 

 the eye, a large plate, separated from the nostrils by two quite 

 small plates, at the anterior inferior angle of which, is the 

 aperture for the poison. A large plate over the eyes. Two 

 plates much larger than the others, upon the throat. 



The rattle is composed of six corneous portions. The other 

 specimen has eleven rattles. The abdominal plates are 170 ; 

 caudal plates, 24. 



Although the poison of this species is very virulent, an acci- 

 dent is seldom known to occur ; proving its unwillingness to be 

 the aggressor, and that the fangs are used only as weapons of 

 defence, after sufficient warning has been given of its presence, 

 by the rattles. 



The general impression that a rattle is added annually is in- 

 correct. Dr. Holbrook observes, " It is now certain that rattle 

 snakes have been known to gain more than one rattle in a 

 year, and to lose in proportion, the exact number being regula- 

 ted no doubt by the state of the animal as to health, nourish- 

 ment, liberty, &c. I have known two rattles added in one 

 year, and Dr. Backman has observed four produced in the same 

 length of time." 



The power of fascination attributed to this genus, is too ab- 

 surd to require our serious consideration. 



