1883.] Geology and Paleontology. 309 
forms, are doubtless Miocene, but these of North and South Caro- 
lina are more difficult to pronounce upon, yet, on the whole, Pro- 
fessor Heilprin is of opinion that they should be classed as upper 
Miocene rather than as Pliocene. 
The Atlantic Miocene may therefore be considered to form 
three groups: First, the Upper Atlantic Miocene or Carolinian, of 
the North and South Carolina deposits ; second, the Middle Atlan- 
tic Miocene or Virginian, and the newer group of Maryland ; and 
third, the older group of Maryland, and possibly the lower Mio- 
cene beds of Virginia. 
A NEW FOSSIL SIRENIAN.—At a recent meeting of the Philadel- 
phia Academy, Professor Cope read a paper on Dioplotherium, a 
a new genus of Sirenia from the Miocene beds of South Carolina. 
The form is allied to Halicore and Halitherium, but differs from 
both in the possession of two incisive tusks in each premaxillary 
bone. The anterior tusk is large and compressed towards the 
apex; the second is not much smaller than the first. The pre- 
maxillary bone preserved indicates an animal not smaller than the 
dugong. It was named Déoplotherium manigaulti in honor of Mr. 
Gabriel Manigault, director of the Charleston Museum. 
the Amazon region was represented by two gulfs, the one opening 
to the east and the other to the west, and connected by a wide 
strait at the point of closest approach of the terre firme above 
mentioned. These islands were, according to Professor Hartt, 
tofessor Derby’s predecessor, elevated during the early part of 
e Silurian period. Their materials represent three periods, the 
urentian, Huronian and Lower Silurian. 
n the Palzozoic sea were deposited successively formations of 
Upper Silurian, Devonian and Carboniferous ages. They are all 
well represented by fossils, of which many are identical with spe- 
cies of corresponding periods of North America. The Upper 
Silurian is about 1000 feet in thickness, the Devonian has not 
over 800, and the Carboniferous 2000 feet, according to Mr. H. 
H. Smith of the survey. They are exhibited on both sides of the 
"Proceedings American Philosoph. Society, 1879, p. 155. 
