156 Royal Society. 
The whole row of tooth-sacs is contained within a single general 
connective-tissue investment, which is entered at the top by the 
descending process of oral epithelium, whence the enamel-germs 
are derived. 
As they attain considerable length, the forming teeth, which 
were at first vertical, become nearly horizontal, resuming, of course, 
their upright position once more when they come into place. 
The clue to the whole peculiarity of this arrangement is to be 
found in the extreme dilatation which the mouth of the snake 
undergoes. The general capsular investment probably serves to 
preserve the tooth-sacs from displacement ; while, if the forming 
teeth remained vertical after they had attained to any considerable 
length, their points would be protruded through the mucous mem- 
brane when this was put upon the stretch in the swallowing of 
rey. 
: Just as the author has shown in a previous communication to 
be the case in the Batrachia and Sauria, the hypothetical “ papillary 
stage” is at no time present. 
From the oral epithelium there extends downwards a process 
which, passing between and winding around the older tooth-sacs, 
after pursuing a tortuous course, reaches the furthest and lowest 
extremity of the area of tooth-development. Here its cecal end 
gives origin to an enamel-organ, and, while it does so, buds forth 
again beyond it in the form of a cecal extremity. Thus at the 
bottom of this area of tooth-development there is a perpetual 
formation of fresh enamel-organs, beneath which arise correspond- 
ing dentine-organs, or papille, if such they can be called when 
arising thus far away from the surface. 
In essential principle, therefore, the formation of a tooth- 
germ is similar to that already described in mammals aud other 
reptiles, the difference lying principally in the enormous relative 
length of, and the tortuous course pursued by, that inflection of 
the oral epithelium which serves to form the enamel-organs. The 
attachment of the tooth to the jaw is effected by the rapid de- 
velopment of a coarse bone, which is not derived from the ossi- 
fication of the feebly expressed tooth-capsule, but from tissues 
altogether external to it. Nevertheless this coarse bone of attach- 
ment adheres more closely to the tooth than to the rest of the jaw, 
from which, in making sections, it often breaks away. 
The base of the dentinal pulp assists in firmly binding the 
tooth to this new bone, being converted into a layer of irregular 
dentine. 
This “bone of attachment” is almost wholly removed and re- 
newed with the ehange of each tooth. 
