= NP eet 
an 
ACTINOCRINUS. CYATHOCRINUS. 295 
minute ossicula, are admirably shown in this unique and 
most instructive fossil. 
_ Actinoceinus (Wave Encrinite). Lign. 94, fig.1,2. (Wond. 
_p. 585. Sd. pl. xlvii.)—The column is formed of numerous 
_ round ossicula, possesses side-arms, and is fixed by root-like 
_ processes. The receptacle is of an irregular subspherical 
_ form, the arms passing off at right angles like the spokes 
from the nave of a wheel; hence the name. The base is 
- composed of three plates which support five hexagonals and 
one pentagonal, and on these are three other series ; from 
the upper margin of the last, five arms are given off. The 
receptacle is closed by a dome-shaped tesselated covering 
(Lign. 94, fig. 2), having on one side the opening for the 
mouth and vent. The specimen, jig. 1, is a receptacle with- 
out a stem, and with but a few joints of the arms; this is 
the usual state in which these fossils are obtained. ig. 2 
is an Actinocrinite in which part of the brim of the receptacle 
and of the arms has been removed in front, leaving a por- 
tion of the coalesced arms partially surrounding the probos- 
 cideal plated integument that covers the upper part of the 
receptacle ; the figure is from Mr. Miller’s work, and is in- 
troduced to sieeank the structure of these crinoideans.* 
The external surface of the plates of the receptacle in the 
_ Actinocrinites, is generally covered with radiated markings 
and ridges, so that detached plates have been mistaken for 
those of Marsupites; see the restored figure of a Nave 
Encrinite, Wond. p. 654. In some species the receptacle 
is richly ornamented ; but in the specimen figured, Lign. 94, 
jig. 1, the surface has been defaced in consequence of the 
fossil having been immersed in strong acid. 
CyatHocrinus (Cup-like Encrinite). Lign. 95, and Lign. 
92, fig. 2.—The column is formed of round, depressed, per- 
* Miller’s Crinoidea, fig. N. pp. 98—100. 
