W. J, MceGee—Theory of Glacial Climate. 118 
inexpedient or improper to separate the species now arranged 
under Glyptocrinus and distribute them in two or three genera; 
no satisfactory work, however, has yet been done in that direc- 
tion; and if Glyptocrinus Nealli, G. Baeri, G. subglobosus and 
G. fimbriatus are thrown in one section, then I am free to say 
it is better that all shall remain under the present generic name. 
point out their differences in structure would too grea ly 
lengthen this article. It may be done in another communi- 
n. 
ArT. XIV.—On the Present Status of the Eccentricity Theory 
of Glacial Climate; by W. J. McGur. : 
THE recent appearance of an important treatise, in which 
Croll’s theory of secular variations in terrestrial climate is 
given a prominent place,’ has elicited some adverse criticis 
of that theory, by different reviewers, which can only re- 
garded as embodying the current objections to the adoption of 
the eccentricity theory in general. 
in addition to an indefinite general argument such as 
might equally be brought to bear against any intricate and — 
comprehensive theory involving principles falling within the 
domains of diverse nascent branches of science, Gilbert* urges 
three definite and specific objections against the theory: 
i. “If it is true, then epochs of cold must have occurred 
with considerable frequency through the entire period repre- 
sented by the stratified rocks; and iceberg drift, if no other 
traces, should have been entombed at numerous horizons. It 
hot attached, the phenomena appear to indicate local and not 
general glaciation. ooh © 
If the hypothesis is true, the cold of the Glacial epoch 
must have been many times interrupted by intervals of excep- 
tional warmth; but little has been dite to the evidence adduced 
by Croll for such an interruption, and in America, where there 
1S NOW great activity in the investigation of glacial phenomena, ~ 
1“ Text Book of Geology,” os Geikie, 1882, 21-29. ? Nature, xxvii, 262. 
ae our. Sor.—Tarmp Seares, Vou. XXVI, No. 152.—Ave@usr, 1883. 
