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GEOLOGY. » 503 
made to conform to this rule. It is never safe to infer from the 
mere presence of a bird in any particular locality in the breeding 
season that it neccessarily breeds there. I could give you in- 
stances without number where birds are found in summer in local- 
ities, where, so far as one can ever be sure of a negative, we know 
they do not breed. We have seen the black-poll warbler in eastern 
Massachusetts as late as the 10th of June. Yet who supposes it 
ever breeds here? Dr. Abbott’s account escaped my notice, but I 
certainly could not have made it the occasion of any change in 
my statement that the Regulus was not then known to breed in the 
United States. I could only have referred to the interesting fact ` 
of its occurrence, as stated, as suggestive of its possibility. 
Nothing short of its actual nest and eggs would have justified me 
in speaking of its breeding as a certainty. —Tnomas M. Brewer. 
Zoorocy 1s Berarum.—The Belgium Academy has lately is- 
sued two large octavo volumes, as memorials of its hundredth an- 
niversary. The second volume is of great interest to zoologists 
as it contains a review of the progress of zoology in Belgium, by 
the veteran naturalist Prof. P. J. Beneden. 
GEOLOGY. 
SMALL size or THe Brain in Tertiary Mammars.—At the- 
last meeting of the Connecticut Academy of Arts and Sciences, 
June 17th, Prof. Marsh made a communication on the size of the 
brain in Tertiary Mammals. His researches on this subject have 
been mainly confined to the larger extinct mammals which he had 
obtained in the Rocky Mountain region, and the results are of pe- 
culiar interest. The Eocene mammals all appear to have had small 
brains, and in some of them the brain cavity was hardly more ca- 
pacious than in the higher reptiles. The largest Eocene mammals 
are the Dinocerata, which were but little inferior to the elephant in 
bulk. In Dinoceras Marsh, the type genus, the brain cavity is not 
More than one-eighth the average size of that in existing Rhinocer- 
oses, In the other genera of this order, Tinoceras Marsh and 
Uintatherium Leidy, the smallness of the brain was quite as re- 
markable. The gigantic mammals of the American Miocene are 
the Brontotheridæ, which equalled the Dinocerata in size. In 
herium Marsh, the only genus of the family in which the 
skull is known, the brain cavity is very much larger than in the- 
