298 The American Naturalist. [March, 
PROCEEDINGS OF SCIENTIFIC SOCIETIES. 
The Biological. Society of Washington.—The eleventh anni- 
versary meeting was held in the lecture-room of the Columbian Uni- 
versity, on Saturday evening, January 24th, at half-past eight o’clock. 
The retiring president, Professor Lester F. Ward, delivered an address 
entitled ‘‘ Neo-Darwinism and Neo-Lamarckism,’’ in which he took 
strong ground in favor of the latter doctrine. 
February 7th, 1891.—Prof. H. F. Osborn read a paper entitled “A 
Review of the Cretaceous Mammalian Fauna of North America.” It 
was in effect a review of a paper by Prof. O. C. Marsh upon this sub- 
ject, in which six new families, sixteen new genera, and twenty-seven 
new species were described. . He illustrated his remarks upon the 
blackboard, first giving a sketch of the differences between the tri- ` 
tuberculate and multituberculate groups of mammals. He then ex- 
amined in detail the species described as new by Professor Marsh, 
stating that in no case was more than a single tooth described, and in 
l cases this was stated to be the upper molar. He stated it as his 
belief that in numerous instances the teeth were in reality lower molars; 
and he showed by drawings how teeth referred to distinct species, 
genera, and even families, seemed to belong to one species. In onè 
instance he mentioned four families, six genera, and seven different 
species that seemed to belong to one species. 
One tooth which had been described as mammalian he thought 
probably was reptilian, though it was not possible to say positively 
until the lower part was known. ? 
Professor Marsh was present, and replied to Professor Osborn, stating 
that he had seen all the specimens of Cretaceous and Jurassic ; 
of Europe, and had most of those of Cretaceous age from America 1M 
his own collection. He differed in foto from Professor Osborn, and 
had specimens which showed Professor Osborn was entirely mistaken 
in his assertions. He defended his method of describing and illus 
trating a single tooth, believing it to be better to describe 4 
typical example, at least in a preliminary paper, rather than more hat 
one not so perfect or typical. He believed the Cretaceous fauna - > 
have been a large one, the mammals varying from one the size e ae 
shrew to one as large as an opossum; and when he had leisure " : 
describe and illustrate the thousand specimens he now had of CHE S 
