CALYPTOCRINIDAL. 
Monocyciic. LOWER BRACHIALS AND INTERBRACHIALS FORMING AN IMPORTANT PART 
OF THE DORSAL CUP. RADIALS IN CONTACT ALL AROUND. ARMS RESTING IN 
COMPARTMENTS, FORMED BY PARTITIONS ATTACHED TO THE TEGMEN. PLATES OF THE 
CALYX LIMITED TO A DEFINITE NUMBER. DorRSAL CUP, EXCEPT THE BASE, PERFECTLY 
PENTAMEROUS. 
Analysis of the Genera. 
Basals 4. 
1. Partitions extending to the tips of thearms . ...... - EUCALYPTOCRINUS. 
2. Partitions enclosing only the lower portions of thearms . . . . . . CALLICRINUS. 
Geological and Geographical Distribution. 
Number of known species. 
(Open figures indicate American ; those marked (), European.) 
ForMATION. CALYPTOCRINIDE. 
Approximate 
General. American. European Eucalyptocrinus. Callicrinus. 
Equivalents. 
Devonian. Eifel. (1) 
Upper Silurian. Niagara. ven 17 (10) 4 (8) 
1 : + (fez = : 
Total species 40 1 (19) wip (ali) 1 (8) 
Remarks. — Roemer proposed the family name “ Eucalyptocrinid ” 
(Lethaea Geognos. (Ausg. 3), 1855, p. 229), which Angelin in 1878 changed 
to Calyptocrinide. The latter name was accepted by Zittel, who errone- 
ously included with it Zyriserinus Hall, which is a dicyclic Crinoid. 
The Calyptocrinide agree substantially with the Dolatocrinites section of 
the Melocrinidx in the construction of the dorsal cup, but their basals occupy 
the bottom of a deep concavity, and they are remarkable for having the 
