Paranacyathus magnipora (~ Archaeocyalhus magnipora 
Bedford, 1934.) 
Fresh material of this species (see Memoir No. 1, p. 2, 
Fie, 7), shows that it grows from an irregular, Archaeo- 
pharetra-like spitz; see Plate XXXVL, Fig. 142 A. 
Sketches of the upper part of the same and two other 
° specimens are given in Plate XXXVII, Figs. 142 B—E. 
Larger fragments of this species indicate a conical tube 
reaching about 15 mm. diameter in a length of about 
15 em, ‘The structure indicates transferring the species 
to the genus Paranacyathus. As will be seen by com- 
paring the six species just described, there is consider- 
able divergence of detail; in particular the three last 
mentioned species differ from the first three, and agree 
among themselves, in possessing large irregular septal 
pores; in this feature they resemble the Metacyathine 
genera Metacyathus and Metaldetes. 
A Note on Archaeocyathus floreus (Bedford, 1934). 
Since we first described this species, further material 
found has introduced complications which are difficult 
to clear up. Of ten spitzes six show an abnormal, irregu- 
lar structure; two of these are figured 143 A, B. - The 
first shows reduction of septa and development of irregu- 
lar dissepimental tissue; possibly this is the result of 
injury and repair. The second, together with four 
others not figured show normal septa, but considerable 
development of dissepimental tissue. 
hand four of the spitzes are normal in all respects, with 
little or no dissepimental tissue. In the smallest spitz 
seen, which is normal in other respects, the lowest sec- 
tion shows the septa united centrally, with disappearance 
of central cavity. : 
Among the larger specimens, which we have taken as 
being A. floreus, two distinct arrangements of septal pores 
occur. In one the septal pores are confined to a single 
row close to the outer wall; in the other they are in three 
or four rows regularly distributed through the whole 
width of the septum. 
We have also found at the Ajax four specimens 
which agree in all respects with A. floreus except that 
the flutings, which give the characteristic flower-like 
transverse section, are absent. One of these gives just a 
slight fluting in places; one specimen shows the single 
row of septal pores; another shows the distributed septal 
pores. 
In unsilicified material from Ardrossan we have found 
two small specimens, Fig, 144 A, B, which have consid- 
erable resemblance to A. floreus, although the outer 
wall pores, which in 4., floreus are very distinctive, are 
not visible, nor do flutings appear to be present. Both 
these specimens show dissepiments. In these Ardros- 
san forms, the septa, though widely spaced, are much 
closer than in A. floreus; consequently the inner wall 
pores are in a single row to the intersept, whereas, in 
A. floreus, though this occaiosnally occurs near the 
spitz, there are usually two, three or more rows to the 
intersept in larger specimens. 
On the other. 
ox 
vo 
Order ARCHAEOCY ATHINA (Okulitch, 1935). 
Species Archaeocyathus subacutus (Bedford, 1934). 
On Plate XXXVII, Fig. 145 A—D.is shown some 
fresh material to illustrate points not clear in our orig- 
inal specimens. — Fig. 145 D is a small spitz, the typical 
structure continuing to a diameter of little over 1 mm. 
Fig. 145 A is a fragment of the upper part of a large 
delicate expanded specimen. Fig. 145 B confirms our 
surmise that septal. pores are confined to a single row ot 
small pores just within the outer wall. | 
New Species Archaeocyathus aequisemis. 
This is a scarce conical stoutly built form. The type 
specimen is surrounded at the base by a mass of the 
tissue described earlier in the present paper as Exocya- 
thus (q.v.):—See Plate XXXVIII, Fig. 146 A. The 
central cavity in the base is also partly filled with endo- 
thecal tissue. The intervallum coefficient is about 3 
mm.: 20 mm. The pores of both walls average two 
to 1 mm.; hence the name. In both walls the pores are 
regularly arranged in quincunx and in regular verticai 
rows, avering three rows to the intersept. There is a 
strong tendency at the outer surface of the inner wall to 
formation of vertical ridges between the rows of pores, 
Fig. 146 E. The septa are stout, a full mm. apart, 
and are usually thickened towards the walls, particu- 
larly the inner wall; septal pores are small, in about 
six rows, and no stirrup pores are present. Fig. 146 ۰ 
New Species Archaeocyathus aequitriens. 
The type Fig. 147 A is practically the only branched 
Archaeo specimen which we have been able to grind out 
from the matrix. The intervallum coefficient of one 
of the branches is 2 mm.: 12 mm. In both walls the 
pores are regularly arranged in quincunx and average 
three to 1 mm. (whence the name), The pores aver- 
age two or three rows to the intersept. The septa are 
about 3 mm. apart and, over the width of the septum, 
pores are few and irregularly distributed; but, at the 
junction with the inner wall, stirrup pores are invari- 
ably present, Fig. 147 D. E; the inner wall thus has.a 
row of stirrup pores in the line of the septum with one 
or two further rows of pores within the intersept, agree- 
ing in this respect with A. ajax. Fragments of large 
expanded cups of this species have been found. In 
two of these fragments abrupt change of direction of the 
septa is noticeable Fig. 147:F, G, H. One of these 
specimens shows curious branched ridges of the outer 
wall surface, Fig. 147 F, I; from the relationship of 
these to the pores they appear to be part of the wall 
structure. 
New Species Archaeocyathus endothecalis. 
This is a scarce, stoutly-built, conical form (Fig. 
148 A). The intervallum coefficient is 24 mm. : 10 
mm. The central cavity in the lower part is filled with 
coarse endothecal tissue (Fig. 148 B). The outer wall 
pores are regularly arranged, polygonal, and closely 
set, about three to 1 mm. ‘The septa are 14 mm. apart: 
no septal pores are present at all, with the exception of 
stirrup pores, which are 'always present at the inner 
wall, and which, at least in one specimen, are equally 
