lar shelyes oi bars are the main feature. 
. Cyclocyathus. 
tion to the similarity, 
copied a 
Three sections of a small spitz, looked at from be- 
low, are shown in Plate XLV, Fig. 181. At A the 
commencement of the inner wall appears to be closed 
below, and two septal rods are seen, the tube here 
being 7/16 mm. diameter. 
Plaie XLV, Fig. 182, shows, at a diameter between 
$ min. and I} mm., transition from septal rods to septa 
in a spitz of ajex-relezona type. 
Plate XLV, lig. 183, shows transverse, and three 
successive oblique longitudinal sections of 1 mm, spitz. 
Species at the Ajax Mine closely related to Ajacicya- 
thus ajax are Ajacicyathus retezona (Taylor's Archaeo- 
cyalhus retezona), Ajacicyathus stapipora (Taylor's 
Archaeocyalhus stapipora) and Ajacicyathus aequi- 
iriens, endothecalis and brunhilda Bedford. . Other 
species, but without any stirrup pores in the inner wali, 
are Ajacicyathus subacutus, aequisemis, carmen and 
divaricatus Bedford. 
Other South Australian genera of this family are 
Cadniacyathus Bedford and Zonacyathus Bedford. 
Family Bronchocyathidae Bedford. 
Archaeos growing from a spitz of Alphacyathus type 
and developing a specialised inner wall in which circu- 
The outer 
well is of normal, finely porous type. 
The first and best known species of this family was 
described by Taylor in 1910 as Archaeocyathus 
trachealis. Vologdin in 1931 described three similaı 
species from Siberia, giving them the new generic name 
By the way, Vologdin, in calling atten- 
accidentally confused two specific 
the. paper by Gordon, and referred to and 
photograph as tubavallum when evidently 
was intended. Vologdin did not specify a 
but, if he is agreeable, we would suggest 
as Deis much the most completely known 
In the meantime we had given the new name 
names in 
trachealis 
genotype, 
trachealis 
species. 
 Bronchocyathus to this and other Rose being misled 
at a first reading of Vologdin's paper, by the identifi- 
cation of his genus with tubavallum, which we now see 
was a mere lapsus calami on his part. We are there- 
"fore adopting Vologdin's generic name for the forms 
near trachealis and wish to retain our name Broncho- 
cyathus for those with a more complex inner wall like 
Taylor's Ethmophyllum dentatum, and the family name 
Bronchocyathidae for 
. related genera. 
both of these as well as other 
Genus Cyclocyathus, Vologdin. 
There is a single circular shelf corresponding to each 
horizontal row of pores in the inner wall. Cyclocyathus 
- trachealis (Taylor’s Archaeocyathus trachealis) is the 
first described and best known form, heing one of the 
commonest species at the Ajax Mine. 
Several small spitzes have been examined by us. One, 
clearly identified from the upper part as Cyelocyathus 
-trachealis, is shown in a series of transverse sections in 
75 
Plate, XLV, Fig. 184. This spitz is of Alphacyathus 
type. and is traced down to a diameter of 5/16 mm. 
where rods are appearing, whilst at about $ mm. the 
inner wall is indicated. rig. 185 is a longitudinal sec- 
tion of another small spitz 2/3 to 1/3 mm. diameter 
which is probably also trachealis. ‘lransverse sections 
of another trachealis spitz at a higher level are shown 
(on a smaller scale) in Fig. 180; at 1 mm. diameter 
septa are well established and, between 13 and 2 mm. 
the cnaracterisué shelves ot the inner wall show as’ 
anular thickenings. An identified unsilicified fragment 
is shown in median longitudinal section in Fig. 187; 
at tne diameter sketched, 1 mm., the septa have a more | 
open reticular texture than is apparent in the silicinea 
specimens. Lhe spitz or 3 mm. to Lë mm, diameter 
suown in lig, 184 explains clearly the origin or me 
circular shelves; at 1? mm. the inner wall pores are 
sti in quincunx, with no sign ot shelves; shortly above 
this ciameter little inward projections appear above” 
each pore, and soon unite as wavy horizontal lines; 
between this and the 3 mm. stage the pores rapidly lose 
their. quincunx arrangement and the wavy shelves 
straighten out, so that at 3 mm. diameter the charac- 
liit adult form is developed, the wall pores being 
in regular quadrate arrangement—one horizontal row 
of pores between each pair of shelves and one vertical 
row in each intersept. 
T. H Ting gave in 1937 (l.c., p. 347) an entirely 
different description of the development of trachealis. 
showing the septa as all arising successively by invagi- 
nation trom the outer wall and the shelves arising de 
novo as rings joining the inner ends of the septa, with- 
out any intervening stage of a porous inner wall. The 
material we have worked on is quite definite ånd gives 
no confirmation of Ting's description. 
Cyclocyathus trachealis is a widely distributed species, 
having been found by Gordon in Antarctica, and 
Vologdin describes three other species from Siberia. 
Cyclocyathus sigmoideus (Bronchocyathus sigmoideus 
Bedford) is another species from the Ajax Mine. We 
have found an unusual type of tabular structure to occur 
sporadically in Cyclocyathus, and Taylor's “Coscino- 
cyathus" anlax is almost certainly a member of this 
genus and not a Coscinocyathus. 
Genus Bronchocyathus Bedford. 
We wish to retain this generic name for members 
of the family having large spinous and other structures 
projecting into the central cavity and superimposed on 
a system of circular shelves. Bronchocyathus dentatus 
(Taylor’s E ¿thmo phyllum dentatum), which will become 
the genotype, is clearly to be derived from a trachealis- 
like form by further extension of the shelf material into 
the central cavity. Bronchocyathus | tracheodentatus 
Redford is a similar form, 
Vologdin's species Ethmophyllum karangani and 
caveaquadratum may be ا‎ of or near inis 
family. 5 ۱ 
