diam., averaging two pores to the mm., see Fig. 106 C. 
The intervallum coefficient averages 2 mm.: 2 mm., the 
central cavity being narrow. In its branching form 
and the general character and scale of its tissues 
Protopharetra furca has a very strong resemblance 
to Bornemann’s Sardinian species Protopharetra 
polymorpha | (Versteincrungen Sardinien, 1886, 
Plate V). 
Bornemann, in the work just quoted, gives on Plate 
XXXII very fine photographs, in transverse and longi- 
tudinal sections, of a Canadian form which he states 
to be Archaeocyathus profundus (Billings). These 
photographs show.what we, on the lines of our present 
paper, should describe as an Archaeo cup surrounded 
by. several more or less concentric laminae of an 
“Exocyathus”-like parasitic growth. The central cup 
itself, in. the transverse section, looks “Protopharetra”- 
like, but in the longitudinal section, waved septa are 
seen, together apparently with dissepiments, thus 
resembling our “Metacyathus.” Figures of profundus 
were also published by Walcott and by Hinde; most of 
these figures show resemblances to what we have called 
“Metacyathus”; but Walcott's Plate II, Fig 3, 3a (1886) 
is more “Archaeocyathus”-like. At a risk perhaps of 
“making confusion worse confounded,” we suggest for 
the consideration of American and Canadian workers 
enquiry whether more than one form has been included 
in descriptions of A. projundus, what is the relationship 
to the Australian “Metacyathus,” and whether a para- 
sitic growth is present on some of the specimens. 
Our fossil is thus particularly interesting for the 
contact it makes in itself with the Sardinian Proto- 
pharetra polymorpha and in its surrounding zone with 
the Siberian Labrinthomorpha and the Canadian A. 
profundus. 
New Species Protopharetra radix. 
This is a scarce little cylindrical form which it is 
difficult to correlate with other species. The holotype is 
9 
3 mm. diameter, cylindrical. The outer wall is thick 
and clearly defined, but pores cannot be made out, 
possibly because of being obscured by secondary 
silicification. The interior is occupied by an 
anastomosing mass of bars. The bars are not circular 
in section, but flattened, with rounded corners; their 
direction is sloping, but they approach a longitudinal 
rather than a transverse orientation. There is no inner 
wall or central cavity. Pending revision of the whole 
eroup we label it Protopharetra, though it is evident 
that the one generic name cannot cover such distinct 
types as this and P. furca. Our specimen is shown in 
trans, sec. in Plate XXVII; Fig. 107 A, and in longit. 
sect., Fig. 107 B. 
New Genus Flindersicyathus. 
Dr. Okulitch has recently pointed out (Cincinatti 
meeting of Geel, Soc. Amer. 1936) that the generic name 
Spirocyathus was wrongly used in the first instance and 
must be abandoned. There occur at the Ajax Mine 
several species hitherto known as “Spirocyathus” which 
are characterised by an intervallar tissue of curved 
28 . 
hexagonal-tubular lattices (see our Memoir No. 2, p. 15) 
and by an inner wall with large pores leading upwards 
and inwards into the central cavity. For species pre- 
senting this combination of characters we propose the new 
generic name Flindersicyathus, to include the species 
irregularis, (?) multifidus, ptychophragma, and rete, 
together with four new species herein described. 
Pycnoidocyathus is regarded as a development of this 
type. 
New Species Flindersicyathus decipiens. 
There occur at the Ajax Mine two species of “Spiro- 
cyathus" which are very similar in general appearance, 
in the intervallar mesh and in their inner walls. One 
of these: is described by Taylor as Spirocyathus 
irregularis, and is shown in photographs 93 and 94, 
Plate XVI of his 1910 Memoir. In this form the inter- 
vallar mesh, as seen in radial longitudinal section (see 
lower left part of Taylor's photograph 94), shows a 
horizontal orientation of the rod-lattices near the outer 
wall, changing to a downward dip near the inner wall; 
in a tangential section just below the outer wall (see 
left-hand of Taylors photograph 93) the maze-like 
arrangement of the rods is characteristic. We figure 
the outer wall of this species in Plate XXVIL Fig. 108 A; 
and a transverse section in 108 B. There is no defined 
porous plate forming the outer wall, the pores being 
merelv the interstices between the elements of the 
superficial maze of rods, and this maze further throws 
outwards numerous short tubercles (see upper part of our 
Fig. 108 A, and upper part of 108 B). In consequence 
sections of F. irregularis often look as if the outer wall 
is missing (see left-hand side of Taylor's photograph 94). 
Our new species, Flindersicyathus decipiens, has a more 
defined porous outer wall, without protruding tubercles; 
this is shown in Fig. 109 A, B. The pores are small and 
numerous, about 4 : 1 mm. Besides this difference, the 
intervallar lattices, instead of being more or less hori- 
zontal in their outer half, as seen in radial section in 
F. irregularis, in this species have a more uniform, 
downly dipping curve, resembling in this respect F. 
ptychophragma (see our Memoir No. 2, Plate XIV, 
Fig. 67 A, lower part). In both these species the ele- 
ments of the intervallar mesh average less than 1 mm. 
apart, about three to 2 mm. The inner wall is similar 
in both (see our Plate XIII, Fig. 64 D), the pores being | 
about one to 1 mm. The intervallum coefficient is 
3 mm, : 5 mm. 
New Species Flindersicyathus circliporus. 
The outer wall is of the same type as in F. decipiens, 
but the pores are definitely larger and are spaced three 
to 1 mm. The intervallar mesh is more open, the 
elements averaging a full mm. apart. The inner wall 
is more openly porous, the pore walls being narrower 
in proportion to the area of the pores, and the pores are 
more numerous in a given longitudinal distance, about 
three to 2 mm. See Plate XXVII, Fig. 110 A, 110 B. 
The outer wall shows shallow, wavy, transverse corru- 
gations, and the intervallum coefficient is about 8 
mm. : 12 mm. 
