Ajacia Ajax, N. Sp. Plate VIL, Fig. 37. 
This fossil consists of densely silicified, mamillated, 
laminated masses shown at BBB. The apices of several 
Archaeocyathus cups are seen imbedded in these masses 
at AAA, and a broken fragment of a flattened, expanded 
Archaeocyathus occurs at D, within the laminae of the 
Alga. The unsilicified limestone matrix is shown in the 
figure by -cross hatching, and the scribbled shading 
represents broken silicified masses which are in part 
fractured sections of the supposed Alga. The top of the 
figure (at C) no doubt corresponds to the top of the 
specimen in its natural position, as Archaeo cups are 
also embedded in the back surface of the specimen; 
the horizontal band of limestone crossing the lower part 
of the figure would thus correspond to a plane of bed- 
° ding. The white or lightly shaded areas BBB are the 
natural mamillated surfaces of the Alga; a sharply 
re-entrant dimple is seen at C. In several places on the 
fractured surfaces the fossil can be seen to consist, of 
two or three laminae which follow the surface contours. 
The specimen is too coarsely silicified to show any fine 
structure. 
The specimen is a naturally weathered fragment found 
on the surface of the ground at the Ajax Mine, and, 
though careful search was made, no other examples 
could be found. 
The fossil is interesting as showing an extraneous 
means of support for delicate Archaeo cups, and helps 
to explain the common absence of root tissues in the 
Ajax specimens. 
New Genus. Beltania. 
Dense limestone masses having a characteristic fracture 
like that of kidney-iron-ore, and an ivory-like grain, the 
latter being due to a multitude of fine threads in parallel 
orientation aggregated in wavy plates about 3 to 1 mm. 
apart. Genotype:Beltania Beltana. 
Beltania Beltana, N. Sp. Plate VII., Fig. 38. 
It was noticed, in handling the good fossiliferous 
material from the Ajax, that whereas some specimens are 
10 
tough and resistant to crushing, others fracture readily . 
and these latter often show a very characteristic natural 
fracture which has somewhat the appearance of the 
mamillated fracture of kidney-iron-ore. A shows this 
characteristic fracture at the upper part of the sketch, 
the lower cross-hatched part representing the normal, 
unorientated fracture of the limestone. On slicing and 
polishing the material with the characteristic fracture it 
shows a grain like that of ivory, and under low magnifi- 
cation this is seen to be due to a multitude of fine threads, 
dull white in color and with a parallel orientation, shown 
in sketch B. Another surface of the same specimen, 
polished on a different plane, give the appearances of 
sketch C. 
One specimen, not that figured, has rather a striking 
appearance. The mass of Beltania is a band over 2 
inches thick, pale in color, with the characteristic ivory 
grain; the remainder of the matrix is a black limestone 
full of Archaeo fragments; the two meet in an irregular 
wavy surface. 
Beltania probably forms a very considerable per- 
centage of the bulk of the Ajax limestone. Although 
Archaeos are generally considered to be calcareous, this 
cannot be regarded as certain; should they prove to be 
siliceous, the calcareous reef-matrix might be of algal 
origin. 
Professor W. J. Sollas, in a recent letter, says: “If 
they (the Archaeocyathi) were siliceous I should put 
them down without hesitation as Hexactinellida.” 
SPONGES. 
Uranosphaera hexaster (see Part 1, p. 7, Fig. 36.) 
Fig 39 shows a somewhat similar Sponge. The 
specimen, which, like those previously described, is 
fragmentary, is one-half of a sphere 12 mm. diameter. 
It appears to be invaginated at the point marked by an 
arrow, giving a gastrula-like form. Welded to the 
outside rim of the “blastopore” is an excellently defined 
fragment of a six-rayed spicule. This is not seen in 
Fig A; it occurs just behind the arrow, and is shown in 
Fig. B. Fig. C shows one of the small flat six-rayed 
spicules on the outer surface of the sphere. Fig. D 
shows a very small spicule, apparently of many-rayed 
type, from the inner invaginated sphere; the longest ray 
projects inwards into the cavity. This spicule can just 
be seen in Fig. A; to the right of it is a similar spicule 
with the longest ray pointing obliquely outwards. 
Fig. 40 shows a similar Sponge, the fragment being 
half of an ovoid. This has a small invaginated lip (see 
A and C), in which are seen sections of small spicular 
rays, but these are not so prominent or well defined as 
those in the other specimen. As before, small six-rayed 
spicules occur in the outer surface of the ovoid. 
The group of spicules shown in Fig. 41 occurs in 
connection with a curved, ill-defined layer of poor 
silicification in which are several unsilicified "ghosts" 
of many-rayed spicules. One of these “ghosts” is seen 
at c. The many-rayed spicules shown at a and b are 
very close to the layer of “ghosts” and those ends of the 
rays which are still buried in the matrix would reach 
down to that layer. The “ghost” spicules rather re- 
semble those of the small-spiculed sponge referred to on 
p. 7 after Uranosphaera polyaster. 
GROUP OF LARGE SPONGE SPICULES. 
Fig 42 shows two views of a piece of limestone which 
includes numerous fragments of large spicules. The 
greater number of these fragments lie in a circle (see 
left-hand figure); but whether this arrangement is 
