216 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
Geological and Geographical Distribution. 
Number of known species. 
(Open figures indicate American, those marked ( ), European.) 
ForRMATION. RHODOCRINID2. 
American. 
Approximate 
Equivalents. 
European 
| Rhaphanocrinus. 
| Archeeocrinus. 
| Diabolocrinus. 
| Thylacocrinus, 
| Lyriocrinus. 
| Anthemocrinus. 
| Ripidoerinus. 
| Diamenocrinus. 
Keokuk. 
| roe) | Rhodocrinus, 
Suds 
— 
Upper Burlington. 
= 
| rs ic os bo | Gilbertsocrinus. 
Lower Burlington. 
Mountain 
Limestone. 
Kinderhook. 
= 
c 
I 
o 
S 
& 
a 
= 
So 
~ 
2) 
a 
cH 
= 
= 
So 
2 
= 
J 
o 
2 
2) 
mM 
rn | ol 
- | 
Hamilton. Up. Devon. 
= 
bo 
Ww 
Upper Helderberg. | Eifel bed. 
Wenlock. 
Gotland. 
“= 
bo 
wo 
Devenian. 
Niagara. 
Hudson River. 
Silurian. 
Trenton. 
Total species 54 | (is) (7) (4) | @) 
Remarks. — When Roemer established the Rhodocrinids, he was ac- 
quainted only with the genus Rhodocrinus, in which he included also the 
species which were afterwards referred to Ripidocrinus and Gilbertsocrinus. 
He omitted Acanthocrinus, which he had himself proposed in 1850, probably 
having discovered its identity with Rhodocrinus. 
The earlier French writers, d’Orbigny, de Koninck, Pictet, and Dujardin 
and Hupé, placed ?hodocrinus with the Cyathocrinide. 
The Rhodocrinide of Zittel and de Loriol embrace Rhodocrinus, Olla- 
erinus, Acanthocrinus, Ripidocrinus, Hadrocrinus, Trybliocrinus,* and Thysano- 
* We have not seen Geinitz’s description, but judge from Zittel (Handb. der Paleont., Vol. L, p. 377) 
that it is a doubtful or imperfectly defined genus. 
