1891.] Geology and Paleontology. 137 
eneral Notes. 
GEOLOGY AND PALEONTOLOGY. 
Discovery of Fish Remains in Ordovician Rocks.—At a 
meeting of the Biological Society of Washington on February 7th, 
1891, Mr. Charles D. Walcott, of the U. S. Geological Survey, an- 
nounced the discovery of vertebrate life in the Lower Silurian (Ordo- 
vician) strata. He stated that ‘‘ the remains were found in a sandstone 
resting on the prepaleozoic rocks of the eastern front of the Rocky 
Mountains, near Cafion City, Colorado. They consist of an immense 
number of separate plates of placoganoid fishes and many fragments 
of the calcified covering of the notochord, of a form provisionally re- 
ferred to the Elasmobranchii. The accompanying invertebrate fauna 
has the facies of the Trenton fauna of New York and the Mississippi 
valley. It extends upward into the superjacent limestone, and at an 
horizon 180 feet above the fish beds. Seventeen out of thirty-three 
species that have been distinguished are identical with species occurring 
in the Trenton limestone of Wisconsin and New York. 
« Great interest centers about this discovery from the fact that we 
now have some of the ancestors‘of the great group of placoderm fishes 
which appear so suddenly at the close of the Upper Silurian and in the 
lower portion of the Devonian group. It also carries the vertebrate 
fauna far back into the Silurian, and indicates that the differentiation 
between the invertebrate and vertebrate types "probably occurred in 
Cambrian time.” 
of America, in August, 1891. 
