FOSSILS OF THE LIAS. 357 
most part common to the superior group marked by A. 
BucklandL Fig. 3 T 2 . 
Among the Crinoids or 
Stone-lilies of the Lias, 
the Pentacrinites are con¬ 
spicuous. (See Fig. 373.) 
Of Palceocoma ( Ophioder- 
ma) Egertoni (Fig. 374), 
referable to the Ophiuri- 
dm of Muller, perfect spec¬ 
imens have been met with 
in the Middle Lias beds of 
Dorset and Yorkshire. 
The Extracrimis Briareus (removed by Major Austin from 
Pentacrinus on account of generic diiferences) occurs in tan¬ 
gled masses, forming thin beds of considerable extent, in the 
Lower Lias of Dorset, Gloucestershire, and Yorkshire. The 
remains are often highly charged with pyrites. This Crinoid, 
Ammonites margaritatus, Montf. Syn. A, 
Stokesi. Sow. Middle Lias. 
Fig. 373. Fig. 374. 
Eoctracrinus {Pentacrinus) Briareus^ 
Miller. ^ natural size. (Body, arms, 
and part of stem.) Lower Lias, Lyme 
Regis. 
Palceocoma (Ophioderma) tenuihracMata, 
E. Forbes. Middle Lias, Seatowu, 
Dorset. 
with its innumerable tentacular arms, appears to have been 
frequently attached to the driftwood of the liassic sea, in the 
same manner as Barnacles float about on wood at the present 
day. There is another species of Extracrinus and several of 
