BATOCRINIDAE 
47 
This extensive subfamily, typically Carboniferous, and hitherto considered as having 
originated in the Devonian, must now be moved a step farther back in the geological scale 
and credited to the terminal Silurian, as is proved by the occurrence of a well defined species 
in the Tennessee area. 
Aorocrinus nodosus new species 
Plate 10, figs. i6-i6b 
Calyx rotund, with slightly ]n-otnberant base ; plates elevated into sharp 
nodes; iBr few, not connecting with tegmen except at the anal side. Anus sub- 
central without a tube. Tegmen plates smooth, and none of them spiniferous. 
The single specimen upon which this species is based was found in the uppermost forma- 
tion of the Tennessee Niagaran, the Decatur limestone, in a bed which is closely associated 
with the overlying Linden with its characteristic Helderbergian species of the Devonian 
Scyphocrinus. Nevertheless the presence in the same layer of such an unquestionable Nia- 
garan form as Caryocrinus ornatiis leaves no room for doul)ting the stratigraphic position 
of our species, which is thus in accord with the great difference in its facies from that of the 
hitherto known Devonian forms. The extremely rotund and robust calyx and sharply nodose 
cup-plates produce a distinctly new type, for which, however, we may have a connecting link 
in a species from the Hamilton recently acquired, and herewith figured. 
It has been contended that the genus Aorocrinus as founded by Wachsmuth and Springer, 
N. A. Crin. Cam., 1897, p. 470, should give way to Coclocrinus of IMeek and Worthen. While 
this may be true for some Lower Carboniferous species, that genus was founded upon a type 
with very broad, concave base, from which most of the forms referred to Aorocrinus are 
sufficiently differentiated, but which may also have a forerunner in the new Devonian species 
here figured. 
Horizon and locality. Decatur limestone, Niagaran; below Grandview, 10 miles above 
Clifton on the Tennessee River, Perry County, Tennessee. Associated with Mariacrinus 
rotundas. 
Aorocrinus clarkensis new species 
Plate 10 , figs, i/, i/a 
This isolated specimen from the Devonian is figured for comparison with 
the preceding species. Whether it belongs to this genus is not clear, in the ab- 
sence of the parts in the arm-zone. It is derived from the Hamilton beds of 
Clark County, Indiana. 
