22 
PORIFERA. 
New Family URANOSPHAERIDAE. 
The remarkable sponges from the Lower Cambrian of 
Beltana which are described in this and previous memoirs 
as Uranosphaera form a group which appears to be 
worthy of family rank. The sponges of this new family 
may be defined as hollow spherical or ovoid forms of 
considerable size, one or two or more centimeters in 
diameter. The wall is built of a single layer of large 
spicules, each of which is composed of a body and a 
series of rays proceeding from it in the plane of the 
wall; the rays may be six or more in number and may be 
either simple pointed rods or branched, irregular and 
tuberculated structures. Some specimens have a single 
wall, which at one point may show an opening with either 
an everted or an inverted lip; in other specimens the 
inverted lip may be continuous with an inner concentric 
wall, also of spicular structure. i 
So far no connecting rods have been observed between 
the outer wall and the inner (except, of course, for the 
connection at the lip above referred to). 
Specimens are very scarce, and too little is yet known 
about the family to attempt.any general interpretation, 
but the resemblance to the metazoan “blastula” and 
“gastrula? may be noted. As is the case with the 
Archaeos, it is an open question whether the skeleton 
was originally siliceous or calcareous. 
Were 
New Species Uranosphaera ramosa. 
The genus Uranosphaera was described in previous 
memoirs, pp. 7 and 10, Figs. 35, 36, 39, 40. The presen: 
species is founded on a well-preserved fragment which 
appears to be part of an ovoid about 5 cm. in length 
hy 2 to 3 cm. diameter. 
The single wall is substantial, nearly 2 mm. in thick- 
ness, and is composed of a single layer of stout spicules 
whose centres are from 4 mm. to 3 mm. apart. The body 
of each spicule is a dense mass, rising somewhat above 
the general wall surface, and from this body proceed a 
variable number of irregular branching processes which 
Íuse or interdigitate with those of neighboring spicules, 
so that the wall substance between the spicule-bodies is 
crowded with a moss-like mass.of tuberculate branches. 
The fragment of the fossil which is preserved gives no 
indication of an invagination or an inner wall such as 
was found in the specimens of Uranosphaera haxaster 
shown: in Figs. 39, 40, but the fragment is too incomplete 
to exclude the possibility that an invagination may have 
been present. Uranosphaera ramosa is shown in Plate 
XXI, Fig. 89. (A) being a view of the fossil natural 
size, (B) an enlarged view of the surface. 
Order HETEROCYATHINA (Okulitch). 
Family HETEROCYATHIDAE (Bedford). 
New Species Heterocyathus tertius. 
We have recently found a fragmentary specimen of à 
third species of Heterocyathus; for an account of former 
species see pp. 6, 7 and Figs. 34, 35. The new specimen 
is for the most part unsilicified, the substance of the 
fossil etching with acid and leaving cavities in inorganic 
silica deposits in the matrix, so that what were originallv 
pores appear as papilla-like casts. But fortunately a 
small fragment of the outer wall is normally silicified, 
which enables a clear interpretation to be placed on the 
unsilicified parts, and also shows that the type specimen 
of Heterocyathus minor is. as we had suspected, a cast, 
whilst that of Heterocyathus major is a fragment of the 
actual fossil." The silicified fragment of the new fossil, 
which gives an internal view of the outer wall, is excel- 
lently preserved, and is a very remarkable structure. 
Outside is a continuous comparatively thin shell, fused 
to the inner surface of which, and standing out in high 
relief, are a series of radiating, spicular elements. Fach 
of these has a central boss from which proceed a numbei 
of rays (18 in one case). The rays as a rule do not 
branch after leaving the boss; they are, as already stated, 
fused along the whole length to the outer shell, but 
stand out prominently from it, and each ray fuses at its 
distal extremity with a ray from an adjoining spicule, or 
with one ray each from two adjoining spicules. In this 
manner every ray finds either one or two partners, Each 
ray is of minimum size where it leaves the central boss 
and thickens progressively to reach a maximum at the 
point of union with a neighboring element. The pattern 
thus produced is very definite and characteristic. The 
thickening of the rays away from the central boss is the 
reverse of the arrangement found in the isolated spicules 
described in our second paper. From each boss a con- 
necling rod passes inwards to the inner wall. The centres 
of radiation of the outer wall are from 6 to 9 mm. apart, 
The parts of the external shell between the rays are 
pierced by numerous fine pores about 6 to a millimeter. 
The inner wall of the specimen is unsilicified and poorly 
preserved, only a ghost-like shadow of a spicular structure 
being visible. The fossil is the cylindrical upper part of 
a specimen and shows a termination in which the two 
walls unite; the diameter is about 20 mm., the walls are 
about 5 mm. apart. None of the.specimens of Hetero- 
cyathus yet found give a clear indication of the complete 
form. Two alternative reconstructions appear possible; 
either a cylindro-conical form growing from a pointed 
base (as in the Archaeocyathidae), or else a “gastrula” 
like ovoid with rounded base and an inner wall produced 
by invagination (as in some examples of the 
Uranosphaeridae). Heterocyathus tertius is illustrated 
in Plates XXI, XXII, Figs. 90, 91; 90(A) shows the 
fossil natural size; 91(B) (C) two alternative recon- 
structions; 90(B) internal view of the outer wall of the 
normally silicified portion, x 5; 90(E) natural cast of 
an unsilicified fragment, (a) being inorganic silica sur- 
rounding the fossil, (b) spicular rays, (c) spicular boss, 
the white dots silica casts of the pores; 90(C) “ghosts” 
of spicules in the unsilicified inner wall x 5, at (a) there 
is a suggestion of four pore-casts; 91 (A) a reconstructed 
transverse section x 8. 
We add in Fig. 92 some additional sketches of Hetero- 
cyathus minor for comparison with the above. (A) 
