416 CRINOIDEANS. 
tended through all Formations, from the Epoch 
of the Transition series to the present time.* 
No fossil Stelleridans have yet been noticed in 
strata more ancient than the Muschel-kalk. 
As the structure of the fossil species of both 
these families is so nearly identical with that of 
existing Echini, and Star-fishes, I shall confine 
my observations respecting fossil animals in the 
class of Echinoderms to a family which is of rare 
occurrence, excepting in a fossil state, and which 
seems to have prevailed most abundantly in the 
most ancient fossiliferous formations. 
CRINOIDEANS. 
Among the fossil families of the Radiated divi- 
sion of animals, the Geologist discovers one whose 
living analogues are seldom seen, and whose 
vast numerical extent and extraordinary beauty 
entitle it to peculiar consideration. 
Successions of strata, each many feet in thick- 
ness, and many miles in extent, are often half 
made up of the calcareous skeletons of Encri- 
nites. The Entrochal Marble of Derbyshire, 
and the Black rock in the cliffs of Carboniferous 
* I found many years ago fossil Echinidans in the Carbonife- 
rous limestone of Ireland, near Donegal, they are however rare 
in the Transition formation, become more frequent in the Mus- 
chel-kalk and Lias, and abound throughout the Oolitic and Cre- 
taceous formations. 
