398 
ORIGIN OF LIFE IN AMERICA 
Naturally his views gave rise to a considerable amount of 
discussion ,and criticism among geologists and palaeontolo¬ 
gists ; and many visited the scenes of these startling dis¬ 
coveries. Almost all of them felt convinced that Dr. 
Ameghino had wrongly interpreted the age of the deposits 
alluded to. They thought that the fossiliferous beds described 
must be much more recent than Dr. Ameghino supposed, and 
that at any rate South America was certainly not thei source of 
all the mammalia. One of the richest of the deposits exposed 
in different parts of Patagonia, especially in the region of the 
Santa Cruz river, and hence spoken of as the “ Santa Cruz 
beds,” is considered by Dr. Ameghino as of Upper Eocene 
and Lower Oligocene age. Almost all other authorities believe 
them to belong to the Miocene. The latter view seems to be 
strengthened by the results of the study of the marine shells 
contained in beds of similar age which were pronounced by 
Dr. Ortmann * to be of Miocene Age. 'As Professor Scott f 
expresses the opinion that Dr. Ortmann has clearly demon¬ 
strated the Miocene age of the Santa Cruz beds, I should like 
to direct attention to a more recent work dealing with this 
problem. Its author, Dr. von Ihering,[j: has made a special 
study for many years past of the marine mollusks of South 
America. Hence his opinion is of particular value. After 
a long and careful study of a larger series of fossil mollusks 
than was available before, he came to the conclusion that 
the marine Cretaceous deposits of Patagonia pass very gradu¬ 
ally into those of the next formation, which is the one 
described by Dr. Ortmann, the latter scarcely containing 
five per cent, of living species. He is inclined on that 
account to agree with Professor Ameghino as to the Eocene 
and Oligocene age of these marine beds, and thus indirectly 
with his general scheme of correlation. Dr. von Ihering’s 
arguments appear to me more convincing than those of Dr. 
Ameghino’s opponents, and I shall therefore adhere to the 
latter’s nomenclature of the Argentina deposits. Not only 
has Dr. von Ihering adopted Dr. Ameghino’s views, they 
* Ortmann, A. E., “Princeton University Expedition,” Yol. IV., 
p. 317. 
t Scott, W. B., “Mammalian fauna of Santa Cruz,” p. 241. 
\ Ihering, H. von, “ Mollusques fossiles de l’Argentine,” in 95. 
