lxvill DESCRIPTIVE REMARKS. 
The CrinoiwEa occur in profusion ; some masses of Limestone being 
almost entirely composed of their separated joints, is therefore called 
Crinoidal Limestone. Platycrinus levis, fig. 3, affords a good idea of 
one of those ‘‘ stone lilies,” showing a portion only of the column or 
stem,* composed of jointed rings, above which is the head calyx or 
“cup,” built up of large plates from which spring double pairs of 
arms, which again subdivide, and are covered by the fingers, pinnule. 
P. mucronatus, fig. 4, is an allied species showing the proboscis. 
Woodocrinus macrodactylus, fig. 5, is one of a series of remarkable 
Crinoids, named in honour of Edward Wood, Esq., J. P., F.G.S8., &e., 
of Richmond, Yorkshire, to whom, in conjunction with Professor 
De Koninck, of Liége, we are much indebted for their discovery and 
elucidation ;} they occur in a most perfect condition, and in great profu- 
sion, in certain beds of the Yoredale series, in Carboniferous Limestone 
at Swaledale, near Richmond. Poteriocrinus crassus, fig. 6, a, 6, e, is 
portion of a large stem and separated joints, and P. conieus, fig. 7, 
represents a large part of the head of another species. Actinocrinus 
is a very abundant genus; fig. 8 shows a portion of the column from 
which proceed the ramules or side arms. <Actinocrinus polydactylus, 
fig. 9, is a frequent fossil in the Lower Limestone shale, especially at 
Hook Head, county of Wexford, some of the radiated plates of the 
cup and a portion of the stem only are shown in the figure. A. am- 
phora, fig. 10, is a large head common in the limestone at Derryvullan, 
county of Tyrone. 
The EcuinowweAa, or Sea Urchins, include some remarkable bodies 
called Palechinus. One of these beautiful fossils, P. elegans, fig. 11, 
a-d, shows a much larger number of plates entering into its compo- 
sition than is possessed by its recent analogues, together with other 
peculiarities in the ambulacral arrangement, and ovarian or genital 
disk. Archeocidaris Urii, fig. 12, a, b, is a species of which the de- 
tached plates and large spines only have yet been observed. 
The discovery of a new spe-ies of this genus by Wm. Harte, Esq., 
CG. E., and County Surveyor of Donegal,t lately redescribed and 
named by the author.§ <Archeocidaris Hartecana is the only known 
instance where the general form of this peculiar Carboniferous Urchin 
has been preserved. 
The genus Archeocidaris may be considered as the prototype of 
the Cidaris; whilst Palechinus foreshadowed that of Hehinus. 
All the classes of Mollusca except the Zunicata which have no 
hard shell, are well represented, and of full size in the Carboniferous 
Limestone. 
The Potyzoa are more numerous in the Carboniferous Limestone 
and shales than in any other formation; the shales between the beds 
* See diagram of Crinoid, Descriptive Remarks, ante p. xxviii., fig. 7, for designa- 
tion of parts. 
+ “ Geologist,” 1858. 
+ Journal Royal Geological Society, Ireland, Vol.i., p. 67. 
§ Ibid., Vol. v, p. 40, Pl. iv. 
