Plate XL, Fig. 153A-E, are illustrations of fresh material 
of Z. retevallum showing more detail than the original 
ligure 6; the original description gave the outer wall 
pores as a single row to the intersept, we now find a 
double row to be at least equally common. 
۱ 
Ethmocyathus lineatus (Bedford, 1934) . 
, In Plate XL, Fig. 154 A-E, are shown details of addi- 
tional material of this very scarce and interesting little 
species, 
New Species Coscinocyalhus minimiporus. 
This is a very scarce, rather stoutly-built little conical 
Coscinocyathus. The outer wall has a quite regular 
series of pits, about four to 1 mm., bordered by more 
or less crescentic projections; within each pit is a lamina 
perforated by about half a dozen very minute pores 
(Fig. 155C). The intervallum coefficient is 2 mm. : 4 
mm. The septa are 4 mm, apart and, on an average, 
there are three alternating rows of the outer wall pits 
to the intersept. The septal pores are in about ten very 
regular vertical rows of very minute pores to each 
septum. The inner wall pores are three or four to 1 
mm. and hooks are present projecting into the central 
cavity; one or two-rows of inner wall pores are present 
in each intersept (Fig. 155 B, D). Tabulae are fairly 
regular, averaging lj mm, apart; tabular pores are 
numerous and are excessively minute, about sixteen to 
1 mm. (Fig. 155 B). 
New Species Coscinocyathus sylvia, 
Only one fragment has been found of this little 
Coscinocyalhus, which is of unusual type. The inter- 
vallum coefficient is 14 mm. : 7 mm. The outer wall 
has pores which are in pairs, a pair occupying the width 
of an intersept (Fig. 156 B, lower part); projecting 
outwards from the wall are ridges which enclose the 
pairs of pores, and which are produced into papillae 
(Fig. 156 B, upper part). About four of these pore- 
pairs are present to 1 mm. of length. The septa are 
closely set, 4 mm. apart, and about five rows of pores 
are present in the width of the septum. The inner wall 
has a single row of pores to the intersept; two or three 
pores to 1 mm. Tabulae appear to be about 2 mm. 
apart, with pores about eight to 1 mm. 
New Genus Polycoscinus. . 
The genus is formed for the reception of two 
meandering, branching Coscinocyathus-like forms from 
ihe “Paint Mine.” The genotype is Polycoscinus con- 
tortum. Vologdin has given the name Polycyathus to 
Archaeocyathus-like forms of similar habit from Siberia. 
New Species Polycoscinus contortum. 
A meandering, branching form with intervallum width 
of 24 mm. (Fig. 157 A). The outer wall has slight 
vertical flutes between the septa, and also slight hori- 
zontal corrugations about 1 mm. apart (Fig. 157 B). 
Septa average a full mm. apart. Outer wall pores, about 
five to 1 mm.. are regularly arranged in about four 
37 
vertical rows to the intersept; in our specimen they are 
covered externally by a uniform very finely porous pellis 
(upper part of Fig. 157 C) ; we have not seen precisely 
this feature in any other Archaeo. Inner wall pores, 
about four to 1 mm., average three vertical rows to the 
intersept, and vertical ridges are present on the inner 
surface of the wall between the rows of pores. Septal 
pores average six vertical rows in each septum. Tabulae 
occur ai rather wide intervals. 
New Species Polycoscinus complexum. 
The species (Fig. 158 A, B) is of similar form to that 
last described, but is on a smaller scale, having an inter- 
vallum width of 1 to 14 mm., and septa į mm. apart. 
A NOTE ON THE CLASSIFICATION OF 
PLEOSPONGIA. 
Lower Cambrian sponges of South 
following structural types may be 
Among the 
Australia the 
distinguished :— 
l. Biastula and gastrula-like forms, spherical or oval 
in shape, having either a single or double wall ot 
large spicular elements: described by us as 
Uranosphaera. جا‎ the gastrula-like, double-walled 
specimens we have not yet seen bars connecting 
the two walls; but isolated spicules, having six 
rays in one plane (or concave surface) and another 
ray perpendicular to these, suggest such a form 
with connecting, bars, 
2. Double-walled forms with connecting bars between 
the walls; the walls consisting of perforated plates 
to which are anachylosed radiating spicular 
elements. The generic name is Hetairacyathus, in 
substitution for the previously appropriated 
“Helerocyathus.” Dr. Okulitch gave this group 
ordinal rank as an order of the Pleospongia. - Since 
our original description was published, a fresh 
fragment indicates that the general form may be 
that of a gastrula-like ovoid. Should this prove to 
be the case the general form relates Hetairacyathus 
to Uranosphaera rather than to the remainder of 
the Pleospongia, all of which grow from a conical 
spitz. If all these forms are to be included in the 
Pleospóngia, one or probably both of the orders 
Uranosphaerina and Hetairacyathina are sharply 
distinguished by their mode of growth from the 
remainder of the class. 
3. Order Monocyathina (Okulitch). These single- 
walled, conical forms present considerable differ- 
ences of structure among themselves; e.g., Mono- 
cyathus irregularis, with sparse, irregular pores. 
each in the form of a pustule; M. porosus, with 
very regular pores, strongly resembling one of the 
walls of a regular Archaeocyathus; M. spinosus, 
with a more open mesh, and with little spines 
projecting outwards from the nodes of the mesh. 
4. Order Spirocyathina (Bedford) (though the name 
may have to be abandoned, as suggested by Dr. 
Okulitch; if so, perhaps the name Dictyocyanthina - 
will best express the relationship). 
