PEXGELLT— ON THE DEVOXIAX AGE OF THE WOELD. 341 
Ijeing confined to the Silurian rocks ; but is, perhaps, a complex 
sponge."* The fossil is, accordingly, catalogued at present under 
the name of Splicerospong la tesselatus. It occurs in the limestone 
beds at Lummaton, near Torquay, and at Woolborough Quarry, near 
Xewton ; one fine specimen recently found at the latter locality, shows 
that it is cup-shaped, the calyx, which unfortunately is somewhat 
broken, is elliptical, — having, at the top, its greatest diameter, about 
two and three-fourths inches, the least two inches, and narro'U'ing 
almost to a point at the bottom. The depth of the cup is about one 
and a quarter inch. The walls are about one-twentieth of an inch 
thick ; the inner surface is divided into a net- work of quadrilateral 
meshes, by the interlacing of, what may be termed, vertical and 
horizontal ribs. The former are, with slight variations, about three- 
twentieths of an inch apart, and are of two kinds, — primary, extending 
from the bottom to the top of the cup ; and secondary, springing 
from various heights in the side or wall. The primary cycle consists 
of sixteen ; the secondaries occur in pairs one on each side of a 
primary, of which they seem to be two branches issuing from the 
same node ; these, in like manner, occasionally give ofi" similar 
branches. The horizontal ribs are less prominent, somewhat thinner 
and closer than the verticals ; they are about one tenth of an inch asunder. 
Not unfrequently some irregularity is observable in their arrange- 
ment, being occasionally more or less out of horizontal, and not 
always at quite the same level on the opposite sides of the same 
vertical ; so that as often as otherwise, they are not in one and the 
same straight line. In fact they sometimes remind one of the 
"bridging-pieces" which builders insert transversely between the 
flooring joists in houses for the purpose of securing stability. The 
surfaces of both sets of ribs, as well as the interstices, are covered 
with gi^anules. Imagine the cup to be a gigantic calyx of some 
species of coral belonging to the sub-order Zoantharict tahulata, as, 
for example, HelioUtes porosa ; then do the vertical ribs represent the 
rudimentar}^ septa, and the horizontal ones the tabulae, which must 
be considered as rudimentary also.;]; 
The beautiful specimen of this fossil figured in the Transactions of 
the Geol. Soc, vol. iii., part 1st, plate xx., fig. 1 ; and also in Professor 
Phillips' " Palaeozoic Fossils," plate lix., is lodged in the Jemiyn 
Street Museum. 
The genus Stromatopora, formerly regarded as belonging to the 
corals, but now removed to the sponges, contain five Devonian 
species, all of which appear to be confined to British localities, with 
the exception of S. concentrica, which occurs also in the Eifel. It is 
extremely abundant in the South Devon limestones, and not unfre- 
quently attains a very great size. 
* Palaeozoic Fossils, p. 135. 
t Siliiria, 3rd Ed., p. 298. 
t This is merely meant as illustrative, and not as a puggestion that the 
fossil is a coral. 
