Á em^é‏ سس نس 
12 
would be an easier place (one would think) for acci- | 
dental fragments lo accumulate in. Another point is 
that on carefully re-examining the seven specimens of 
Acanthinocyathus available two more of them are each 
seen to have one or two spicules within the intervallum. 
In our first paper we had commented on the spicule-like 
nature of the tissues of Acanthinocyathus; can it be only 
coincidence that actual spicules are now found within 
this organism? 
Another question that naturally suggests itself is that 
of a possible relationship between Acanthinocyathus, the 
large sponge spicules, and Üranosphaera. 
Another Fragment Comparable to Acanthinocyathus. 
This is figured in Plate X. Fig. 45. A shows a 
transverse section; B a tangential view grazing the outer 
wall. To the left of a the outer wall rods dip inwards 
slightly and tubercles are visible similar to those noted 
on the inner wall of the previous specimen. At b the 
outer wall is lost and three of the connecting rods are 
seen in section in the intervallum. 
Order MONOCYATHINA (Okulitch). 
Family MONOCYATHIDAE (Bedford). 
Monocyathus porosus (Bedford). 
Some additional particulars of this species are figured 
in Plate X., Fig. 46. 
A shows a reconstruction (natural size) of a large 
specimen which is much corrugated at the top. B shows 
the top of the specimen with incurved rim referred to 
on p. 2 of our 1934 memoir. C shows an inner view 
of the wall with vertical ridges beiween the rows of 
pores; the appearance is very similar to the walls of 
Dokidocyathus, but in that species the ridges in both 
walls are on the external surfaces of the walls. 
Monocyathus robustus, N.Sp. Plate X., Fig. 47. 
Tubular, 4 mm. diameter; wall nearly I mm. thick; 
Pores numerous, oval or circular, regularly arranged, 
about 1 mm. apart. ) 
Monocyathus sparsipora, N.Sp. Plate X., Fig. 48. 
Similar to M. porosus, but pores about 1 mm. apart. ` 
Monocyathus mellifer, N.Sp. Plate X.. Fig. 49. 
Tubular, 4 mm. diameter; wall nearly 1 mm. thick; 
pores hexagonal, about 2/3 mm. apart, closely set in a 
regular honey-comb pattern, outer surface vertically 
ridged between the rows of pores. 
Monocyathus spinosus, N.Sp. Plate X., Fig. 50. 
Conical; pores large, more or less hexagonal about 
lj mm. apart; numerous spines, nearly 1 mm. long, 
project outwards. 
Order ARCHAECYATHINA  (Okulitch). 
We are deferring consideration of this Order to a 
further paper, but there is one form, viz., Dokidocyathus, 
figures of which had already been prepared for the 
present paper our intention at the time being to associate 
it with certain simple types which we regard as leading 
up to the Spirocyathidae. As the plates with these 
figures have been completed, we deal with Dokidocyathus 
now. Taylor associated Dokidocyathus with Dictyo- 
cyathus in a family Dictyocyathidae. Okulitch places 
this family in the Order Archaeocyathina. Dokidocya- 
thus is a very clearly defined type and is fairly plentiful 
al the Ajax; its regular conical form, and its regular and 
numerous pores, which are seldom obscured by secondary 
silicification, appear to indicate relationship to 
Archaeocyathidae and Coscinocyathidae; in the spitz 
of Dokidocyathus which we have found, and which is 
shown in Fig. 52, the bars are much closer together than 
in the upper part, and increase the resemblance to 
Archaeocyathus; all these forms are no doubt derived 
from a form like Monocyathus. On the other hand. 
Dictyocyathus, as will be seen, appears to be the starting 
point of the Spirocyathus line of evolution, for which 
we propose a new Order, Spirocyathina. It appears 
necessary to separate Dokidocyathus and make it the 
Lype of a new family. 
New Family DOKIDOCY ATHIDAE. 
Regular conical forms; outer and inner walls with 
regular closely-set circular pores; the two walls con- 
nected in the mature state hy remote flattened bars. In 
one form even these bars are absent. The spitz has 
more numerous bars. Contains one genus, Dokidocyathus 
(Taylor). 
Dokidocyathus simplicissimus (Taylor). 
Plate X., Fig. 51, shows the structure of a mature 
specimen. A is a longitudinal section showing outer 
wall to left and right, the middle part being ground 
away to expose the inner wall. In both walls a change 
in size of the pores is noticeable. B is a transverse 
section of the same specimen. 
Fig. 52A shows a longitudinal view of a spitz, the 
connecting bars being much more closely set than in the 
adult; B is a transverse section of the same specimen at 
a rather higher level, with remote bars. 
Plate XI., Fig. 23, is a reconstruction, natural size. 
of a complete specimen. 
Dokidocyathus Nihilum N.SP. Plate XI., Fig. 54. 
Conical tube; intervallum co-efficient 4 mm.: 24 mm. 
Outer and inner wall pores nearly equal in size, numerous 
and regularly arranged, about 2 to 1 mm. Outer wall 
thicker than inner. No trace can be seen of connecting 
rods between the walls; if any are present they must be 
