147 
one of the effects is the early production of the uniform series in 
this region as compared with the upper jaw (Figs. 2, 3 and 4). The 
uniform series of the maxilla does not begin to make its appearance 
till the animal is approaching its full size. 
Fig. 3. Marginal teeth of 
young animal 24,6 em in length 
(skull 3,5 em), a) from the side, pmz 
b) premaxillary teeth from the | 
front (pmx. premaxilla). IJ, III, 20 
IV, V, !as before. DU. S. uni- ate 
— — 
form series. Nat. size. V 
Fig. 3b 
7 pm 
L 
Fig. 4a. Fig. &c. 
Fig. 4. Teeth of young adult (Skull 5 em in length). a) Right marginal from without. 
b) Right palatine from without. ce) Front teeth’) of upper and lower jaws (slightly 
diagrammatic). JJ, IT, IV, V and U. S. as before. In c) the only dentinal portion 
of the “teeth” are the parts indicated as of the fourth and fifth dentitions respectively 
(IV, V). I have not distinguished between the fourth and fifth dentitions in the maxilla, 
because I cannot be sure to what extent the fifth is represented. The dotted lines in 
a) indicate the lines of attachment of the epithelium to the bone. (Nat. size.) 
1) It is not possible to give such a description or figure of the 
upper and lower front teeth as will embrace the conditions found in 
all adult specimens. It is probably safe to say however, that usually 
each of the four so-called teeth possesses, when the process of tooth- 
change has ceased, two constituents. Of these the one nearer the middle 
line in each case is the first to become completely worn down. Some 
specimens may retain these teeth longer than others, this, and other vari- 
ations, being due to differences in the usual areas of contact with the 
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