124 BRITISH PALASOZOIC SPONGES. 
also of linear spicules, which are grouped together, so that the spicular rays 
which extend the length of Sponge form, by their apposition and overlapping 
each other, continuous spicular fascicules, whilst the transverse rays extend singly 
on either side of the vertical rows, and overlap those from the adjoining rows, so 
as to produce an irregular framework. Smaller spicules are irregularly interspersed 
in the intervals between the larger. 
This genus is closely related to Protospongia, Salter, and Dictyophyton, Hall ; 
but the arrangement of its spicular mesh is far less regular than in either of these 
genera, and there are no definite quadrate areas. From Protospongia it is further 
distinguished by the fascicular grouping of the spicular rays in a vertical direc- 
tion. 
9. PincroperMa scituLuM, Hinde. Plate III, figs. 1, 1 a, 1 b. 
1883. PLEcTODERMA scituLUM, Hinde. Cat. Foss. Spong., p. 132, pl. xxxi, figs. 1 
la, 106. 
The fragment of the Sponge-wall which has been preserved is about 60 mm. in 
width and 45 mm. in height ; it probably formed part of a cup- or funnel-shaped 
sponge. ‘The vertical fascicles are about 7°5 mm. apart from each other; there 
are from five to ten spicular rays in close juxtaposition in each fascicle, but from 
their present condition it cannot be determined whether they were laterally 
cemented together or not. The spicules vary greatly in size; the rays of the 
slender forms are not more than ‘09 mm. in thickness, whilst in some of the larger 
forms the rays are °35 mm. in thickness, and 6°5 mm. in length. The rays are 
straight, curved, or occasionally wavy, they usually taper very gradually from the 
central node to their extremities. ‘Traces of smaller spicules can be occasionally 
seen in the interspaces between the larger, and it is probable that they formed 
part of a continuous spicular membrane extending between the framework formed 
by the larger spicules. 
_The type-specimen, the only one hitherto discovered, is preserved on the 
surface of a soft, micaceous, shaly rock. 'The spicules are now mostly represented 
by empty casts, but in some cases fragments of the original siliceous spicules, still 
retaining their axial canals, are preserved. The wall at first sight appears to 
consist of rod-like spicules, crossing each other at right angles, but where the 
spicules are less thickly grouped together the four rays of a spicule springing from 
a centre can be distinctly seen, and at the common centre there is often a small 
circular aperture, indicating a fifth ray extending inwards at a right angle to the 
