Se 
114 Review of Hall and Whitney's Geology of Lowa, 
from the same formations. Those of the Carboniferous 
stones amount to one hundred and seventeen species, and 
these eighty-nine are new or not before described. ; 
The true generic characters of Zeacrinus, Agaric icocrinus 
Agassizocrinus of Troost,—genera which that author had given 
in his catalogue, but of which he had never published ut fil 
deserig are here for the first time given. In this and other 
es has evidently aimed to recognise fully the wi — 
ablishéd anbors of Prof. Troost. He has on page 544 the fo 
owin 
Hoy ara transcribed these observations, as well as the apetil : 
eon tbec of this ate from the MS. of Dr. TRoost’s memoir 
: ae 
is shown a series of three basal plates below the five plates sup 
osed by these a to constitute the base. 
farther sustained by five American species 
‘Some interesting oe are ss for the first time, conn 
ae 
= 
a 
ce 
a 
“ 
series of the oiatee of the body. These relations, as eal | 
other important points for the discrimination of species ee | 
in the diagrams accompanying many of the descriptions WM" 
formula of numbers belonging respectively to the anterior, ante & ) 
a and thee abpers ‘lateral rays. These characters, wee to 3 
new species. hodocrinus is noticed for the first time 
American Carboniferous species. Five species of the genus ra 
cheocidaris are described and rhea one from each of 
limestones of the Carboniferous series. ; 
Report is doubtless the heal contribution yet made “ 
_ knowledge of the Crinoids and other Echinoderms of the 
miferous system; and, both as regards their structure “2 | 
logical distribution, jt is of the highest interest. W 
cite at length important observations on the genera and spesie 
* 
