940 The American Naturalist. [November, 
tubercular. His series is Uintatherium, Coryphodon, Pantolambda ; 
the last the most completely tritubercular. The time order is, however, 
the reverse, viz.: Pantolambda (Puerco), Coryphodon (Wasatch, and 
Uintatherium (Bridger) ; the first the most unmodified tritubercular. 
In accordance with his general position Dr. Ameghino believes (p. 
72) that the quadritubercular genus Procyon is of great antiquity and 
prior to tritubercular types. This, however, cannot be believed. It 
has descended from a primitive plantigrade tritubercular, canine type, 
as have their allies the bears. The same modification is seen in the 
Mustelidz in the badgers; and all such are modern forms. He states 
(p. 26) that in Periptychus and Mioclenus, Phenacodus and Achzn- 
odon, the teeth are quadritubercular. The first two genera have tri- 
tubercular molars with insignificant rudiments of others both before 
and behind the protocone (Periptychus) or behind only (Mioclenus), 
and they belong to the primitive Puerco period. The other two genera 
are quadritubercular, but belong to later beds, Phenacodus being Wa- 
satch, and Achznodon, Bridger, neither of which formations has any 
genus in common with the Puerco (except Didymictis of Puerco and 
Wasatch ages). 
Dr. Ameghino believes the Typotherian suborder of the Toxodontia 
to be related to the Quadrumana. The digits resemble decidedly those 
of that suborder, but one important difference is overlooked by him. 
He has pointed out the striking alternation of the two rows of carpal 
bones in the Typotheria, in which they agree with the Toxodontia 
proper, and with the Amblypoda. Now in primitive Quadrumana 
this alternation does not exist, but the bones of the two carpal rows, 
like those of the tarsus, are directly juxtaposed, or taxeopodous. This 
characterizes the Condylarthra, which furnish the exact foot characters 
of the lemuroids, or ancestral Quadrumana. 
Finally as to Dr. Ameghinos’ views of the origin of the Cetacea, he 
again inverts the order of succession. He does this by assuming that 
the Archeoceti are not related to the Cetacea proper, and cannot be 
ancestral to them. He does not regard the presence of two rooted 
molars in the foetal Balena as significant in this direction. The opinion 
of zoologists and paleontologists has been different from this, and I have 
confirmed the general view in my recent researches on the extinct 
Balænidæ of the Eastern United States.” I have shown that a decided 
sagittal crest like that of the Zeuglodontide exists in some of the 
Miocene whalebone whales. In my estimation the simple teeth of 
many Cetacea are the result of a process of dental degeneration. — 
1 Proceeds. Amer. Philos. Soc., 1895, p. 139; 1896, p 141. 
