386 BREEDING HABITS OF SNAKES—HAY. 
into the world, and that all may be expelled together, is possible; but 
this is not the normal course of things and may not be well for the im- 
mature young. Normally the coverings of such eggs are ruptured 
before birth or immediately afterwards. On the other hand, it is quite 
probable that the eggs of the oviparous species are laid a considerable 
period before they are hatched, ‘The tough coverings of such eggs pro- 
tect them from attacks and injuries from without, and at the same time 
resist the movements of the young snake within. So far as we know, 
these eggs are deposited in the earth, in piles of decaying vegetable 
matter, and similar places. 
A very curious structure deserves mention here. This is the ‘ egg- 
tooth,” a small tooth fixed to the united premaxillary bones and pro- 
jecting forward slightly beyond the edge of the upper lip. It is present 
only in the embryo, and is shed very shortly after the escape of the 
young snake from the egg. In the ovoviviparous species, the tooth 
may apparently be shed before the young are born. The tooth is 
employed by the little snake in ripping open the tough egg-covering 
in its efforts to escape from its prison. It would appear to be of little 
service to the young which are mature when born, since the egg-cover- 
ings are so very tender; nevertheless, | have found the tooth present 
in all the ovoviviparous species whose young I have had opportunity 
to study. This tooth, as found in the black-racer, was described as 
long ago as 1857 by Dr. Weinland;* but Miiller had observed it even 
earlier. 
The Crotalide, including the rattlesnake, the copperhead, and the 
water-moceasin, all, so far as I am able to discover, bring forth living 
young. The number produced at each birth is small as compared with 
the number of young sent into the world by some other species. 
As to the breeding habits of the copperhead, Aghistrodon contortria, 
we have the statement of Dr. J. A. Allent that in Massachusetts five 
out of seven females caught in the latter part of July contained slightly 
developed embryos, while of six killed in September, the oviducts of — 
each contained from seven to nine young, each of which had a length 
of 6 inches. As to the time of the pairing of the sexes, 1 have knowl- 
edge of only one observation. My friend, Rey. A. M. Hall, brought me 
from western Pennsylvania two specimens of this species, which he 
took while pairing, on the 28th of August. Unfortunately, the female 
was disposed of before my investigation of this subject was begun. 
This observation and those of Dr. Allen, when considered together, 
seem to indicate a period of gestation of nearly a year. 
The breeding habits of the water-moceasin, Aghkistrodon piscivorus, — 
are no doubt much like those of the copperhead. A female 26 inches 
long (U.S. Nat. Mus., No. 17968), which was taken on the Arkansas 
bank of the Mississippi River, just opposite Memphis, in the latter days 
*Proc. Essex Institute, Vol. 11, p. 28, pl. 1. 
tProc, Bost, Soc, Nat, Hist., 1868, Vol. xu, p. 179, 
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