820 DR. G. J. HINDE ON RECEPTACULITIDA, 
is also indicated by the delicate concave casts of the outer surface, 
in which the individual plates are marked out by thin raised ridges, 
which are the filled-up spaces which existed originally between them. 
The slightest degree of weathering also is sufficient to clearly expose 
the intermarginal channels and tenuity of the edges of the plates. 
In this form, too, the distal spicular rays, that is, those which point 
to the margins of the cup, project in some instances beyond the 
distal angles of the summit-plates, and extend to nearly the centre 
of the plates immediately in front. Owing, however, to the calcitic 
replacement which has taken place, both the rays and the plates 
over which they extend appear as if welded into one continuous 
mass. 
The horizontal rays beneath the summit-plates are but seldom 
exposed in the specimens of this genus, but in a few instances in 
which the plates have been weathered, they exhibit the same 
character and arrangement as in Jschadites. In vertical sections, 
passing through the centre of the base of the specimens, there is 
shown, immediately beneath the outer surface, a continuous layer, 
from 1 to 3 millim. in thickness, of crystalline calcite, in which no 
structure whatever can be seen; projecting beyond this mass, 
however, there are numerous straight or slightly curved tapering 
shafts or rays which terminate acutely. These rays are smallest in 
the basal portion, and reach their maximum size about halfway 
between the base and the margins of the cup. They project at right 
angles to the summit-plates from beneath which they originate. 
These rays are completely surrounded by the hard matrix of 
greenish grains and fragmentary organisms, and the natural termi- 
nations of several can be distinctly seen. As in Jschadites, they end 
quite free in the concavity of the cup, without being attached to-an 
inner layer as in Receptaculites (Pl. XX XVII. fig.2¢). The thick band 
of crystalline calcite surrounding the interior of the cup appears to 
have been produced by the amalgamation into an undistinguishable 
mass of the summit-plates, the horizontal rays, and the basal 
portion of the vertical rays. 
The distinguishing character of this genus is an open cup-like form 
into which the vertical spicular rays project. It resembles [schadites 
in structural details, but differs therefrom in the absence of a 
covered-in summit, enclosing a central cavity. From Spherospongia 
it is distinguished by the generally rhomboidal form of the spicular 
plates, and the well-developed vertical rays. The absence of an 
inner layer marks this genus off from Receptaculites. For the type 
species, which appears hitherto to have passed under the name of 
Ischadites Kaenigii, I propose the specific name Barrandei. The 
specimens from which the above description is taken are in the 
British Museum of Natural History. 
The only previous notice of this form, of which I am aware, is 
by Ferd. Romer *, who remarks that it differs specifically, if not 
generically, from Ischadites Kenigit, to which it had usually been 
referred. 
* Leth. Pal. Th. i. p. 292. 
