Occasional Notes. 167 
relative to the growth of two young rattlesnakes, 
born and bred in the Museum — and especially as 
to the development of their rattles. Born in Octo- 
ber 1889, these snakes are now about 2\ years 
old ; and they are both of a length of nearly four 
feet. They have fed heartily on mice and small rats 
throughout the time, drinking water quite greedily at 
frequent intervals; and their health evidently is good. 
It is a curious feature that though adult rattlesnakes, 
brought from the country and placed in their cage, will 
rattle at almost the slightest tapping on the edge or 
when they are touched with a wire, these young snakes 
take no notice of such things, but only rattle when a 
large rat, of which they are evidently afraid, or which 
puts them in a state of perturbation, has been placed in 
the cage. 
With regard to the development of the rings of the 
rattle, it was stated in the former account that on May 
27th, 1891, the larger snake (now hardly any larger than 
the other) exuviated, and then possessed six rings, the 
three earliest rings being lost out of its nine exuviations. 
In the smaller, on May 4th, when change of skin took 
place, there were eight rings, these representing the total 
number of exuviations, the last portion being the charac- 
teristic elongated stump with which the little vipers are 
born. 
Now, more than a year after, the former possesses 
5 rings, though three exuviations (on August 14th and 
November 16th 1891, and on March 17th 1892), have 
taken place since May 27th 1891, at each of which an 
extra ring was added ; while the latter has 7 rings, though 
four changes of skin (on July 6th, September 9th and 
