1893.] Succession of the Teeth in Mammals. 499 
molars, like the molars, embraced three single cusps, which were 
arranged in the triconodont type; in Triacanthodon the pre- 
molars are altogether formed like the molars. (This observa- 
tionis an error. The only Mesozoic mammal in which the 
premolars are even approximately similar to the molars, is 
Phascolotherium.) After the original three cusps of the pre- 
molars had been arranged in the triconodont order, he supposes, 
arose the degeneration of the forward cusp, leaving a tooth type 
which’ we observe especially among the Carnivora. (The 
cusps left here are simply the protocone and talon.) 
In an earlier paper upon human dentition, the author is 
also led astray by ontogeny to false conclusions as to phylo- 
geny, and at the conclusion of his extremely interesting paper 
upon the embryogenesis of the human dentition, he says: 
“The typical form of upper molars in man is unquestionably 
the four cusped type; while the typical form in the lower 
molars is the five cusped type.” 
EDENTATES. Dr. Röse has also contributed interesting obser- 
vations upon the rudimentary development of teeth among 
the Edentata. He quotes Max Weber to the effect, that the 
reduction of the teeth in Manis is so absolute, that not a single 
rudiment remains, and that there is, so to speak, no place left 
for the layer either of dentine or enamel. He then goes on to 
say: “ After, in my earlier studies, I recognized the morpho- 
logical importance of the dental fold, and finding it ended as 
a last rudiment of an earlier dentition both in the birds and 
turtles, I did not doubt that also in Manis, at least the first 
stages of a dental ridge must be present in the early embryonic 
development.” With material received from Professor Max 
Weber himself, Dr. Röse demonstrates the beginnings of the 
dental fold both in the upper and lower jaws of Manis ; and 
_ in the lower jaw on both sides he finds even an unmistakable 
rudiment of the tooth layer, in the form of a swollen portion 
of the common dental fold, i. e. an abortive tooth cap. Such 
Tesults were obtained in Manis javanica. 
The forms investigated were the Nine-banded Armadillo 
(Dasypus novemcinctus), Dasypus hybridus, the Pangolin (Manis 
javanica), and the {Anteater (Myrmecophaga.) In the Nine- 
