The American Naturalist. 
(Sl^eneral Notes. 
GEOLOGY AND PALEONTOLOGY. 
Description of a New Genus of Corals, from the Devo- 
nian Rocks of Iowa.— Of the fossil species occurring in the Devo- 
fact is well shown by my own cabinet of fossils, personally collected 
from these strata. Also, many species which are described and have 
long been known to science are, in fact, but very imperfectly known. 
This is owing more particularly to the insufficiency of material hereto- 
fore obtained. 
These statements are especially applicable to the coralline forms of 
nearly all divisions of this formation in the State. 
In this paper will be found a description of a few of these corals 
from the Independence shale and the Rockford shales of Iowa. 
Macgeea, n. gen. — Corals growing in solitary, cylindrical, some- 
times compressed, cup-shape cells ; usually from five mm. to forty- 
seven mm. in length, and calyx from one and a half mm. to eighteen 
mm. in diameter \ slightly curved, externally irregular, usually showing 
ing evidence of attachment. 
Calyx generally as deep as wide, but very rarely being only one-sixth 
as deep as wide ; outer wall thin, rays numerous, from thirty-two to 
seventy-six in number, alternating in size within the cup. 
Costge (often very strong, and usually alternating in size) continuous 
with the rays over the edge of the cup and for some distance below 
the margin ; lower down generally interrupted, or covered with a more 
or less epithecal coat (the epithecal coat is, however, sometimes entire- 
ly wanting), showing traces of numerous transverse partitions. Bottom 
of the cup large, and occupied by a slight depression ; rays sometimes 
very slightly twisted in the bottom of the cup. The rays, and cost^ 
for some distance below the margin of the cup, more or less distinctly 
The description of this genus is based almost exclusively upon the 
species Pachyphyllum solitarium of Hall and Whitfield, although made 
also to include Macgeea culmula of this paper. This genus differs 
conspicuously from the genus PachyphyUum (to which the specimens 
upon which this generic description is based have been referred by 
