384 General Notes. [ May. 
The resemblance of the scapular and pelvic arches of the Pely- 
cosauria' to those of the Batrachia above described, is remarka- 
ble. In Dimetrodon and Clepsydrops, the principal difference to 
be observed in the pelvis, is the much stronger attachment of the 
_ilium to the sacrum. In the scapular arch the principal pecu- 
liarity in the coossified portions, is the posterior double emargi- 
nation of the coracoid. It is thus evident that in the Permian 
period there was a much closer approximation between the Ba- 
trachian, Reptilian and Mammalian types than at any later period. 
—E£. D. Cope. 
BUTHOTREPHIS’ FROM YORK County, PA.—Prof. Frazer has re- 
cently obtained specimens of Buthotrephis flexuosa from the Peach 
Bottom Slate quarries, near the Susquehanna river. The slate of 
this region, according to Prof. Frazer, is bounded, both above and 
below, by chlorites of great thickness, which have been heretofore 
regarded as lying much below the palæozoic rocks. As the 
Buthotrephis flexuosa is characteristic of the Hudson river epoch 
at the summit of the Lower Silurian, this discovery disturbs views 
previously held, and opens up new questions in the stratigraphy 
of the region. ; 
Tue Comstock Lopge.—The scientific history of the Comstock 
has had three periods of development. First came in 1865, Von 
Richthofen, who had carefully studied the eruptive rocks of 
Transylvania, and was able to settle, once for all, the grand 
upon as the real lode-maker. 
The convulsions which attended its appearance were supposed 
to have opened a great crevice into which poured the waters from 
which the ore was deposited, 
1See this Journal, 1878, p. 829. 
