1896.] MAMMALIAN DENTITION. 583 
set which terminates the series. This is borne out by the discovery 
by numerous authors (5, 7, 9, 20) of a lingual growth of the 
dental lamina by the side of the germs of the permanent teeth. 
Fig. 1. Fig. 2. 
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5 772 
Fig. 1.—Diagram of the tooth-succession in a polyphyodont Reptile: 1, 2, 3, 
successive tooth-germs; d./, dental lamina. 
Fig. 2.—Diagram illustrating the relation of a molar tooth-germ (m7) to the 
dental lamina (d./). 
Taking the above into consideration, the presence of true and 
definite outgrowths from the dental lamina nearer the gum than and 
thus labial to the molar germs is extremely interesting and suggests 
that possibly at least one set of teeth preceding the functional 
molars has been suppressed. These vestiges are, it is true, minute 
and variable, but when compared with the obvious vestiges of 
the anterior milk-teeth seen in Hrinaceus it does seem rash to 
conclude that these labial growths in the molar region are the last 
indications of an earlier set of teeth. 
If this is the case, then the molar teeth are not to be referred to 
the 1st, but rather to the 2nd dentition. 
The question then arises, is the milk-dentition the 1st set of 
teeth? This has been answered in the negative by Leche, and I 
hope shortly to publish a further confirmation of this view. 
Leche (7 a) has discovered in the anterior region of the jaw of 
Myrmecobius a minute set of teeth which precede the functional 
set; and as the latter set are now usually regarded as the milk- 
dentition, this vestigial series is termed the pre-milk series, and 
may be compared with those small embryonic teeth seen in the 
Crocodile (19 a) and Iguana (8)’. 
1 Rose (‘‘ Das Zahnsystem der Wirbeltiere,” Ergebnisse d. Anatomie u. Ent- 
wickelungsges., 1894) refers to traces of a pre-milk dentition in Man and 
suggests even an earlier set of teeth in the Vertebrata, a remnant of the placoid 
tooth-papilla, describing in all 5 sets, traces of at least four of which are 
found in the Mammalia. 
