‘hese features are also shown in two other specimens, 
Plate XLIX, Figs. 2U1, 202. 
Uther South Australian genera oi this family are 
Metatdetes taylor and Melacyalhus Bediora; both or 
these genera have well deveiopea radial septa and inner 
walls im lhe upper part, and irregular dissepimentat 
ana trabecular ussue without inner wall or central 
cavity in the lower part, and almost certainly develop 
irom a spitz of Arcnaeopharetra type. raranacyathus 
Beulord, containing a considerable variety OI species, 
also appears to belong to this lamuy, and the same 
may be said of dArdrossacyatius Bearord. Metaldetes 
is described by laylor and the other genera in pre- 
vious pages ol these memoirs. 
Another interesting spitz ot Archaeopharetra type 1s 
shown in Plate XLIX, Fig. 203. ‘Lhe small specimen 
about 6 mm. long by 4 mm. diameter, shown in three 
successive longitudinal sections in Fig. 204, is ol 
Archaeopharetra spitz type. It appears to be closed 
at tne upper end except for a tubular orifice, and may 
illustrate a stage in growth. i E 
The following highly specialised South Australian 
genera are probably related to this family, though in 
many cases the development is not sufficiently known, 
viz.: Archaeofungia مارد‎ and Metafungia, Sigmo- 
fungia, Sigmocyathus and Copleicyathus, Bedford. | 
Among non-Australian archaeos it is suggested for 
consideration that the following, when their develop- 
ment is known, may be found to show relationship to 
the family Metacyathidac. 
Archaeocyathus profundus Billings 
(= Cambrocyathus Okulitch) 
do. _ atlanticus do. 
do. septofidis Vologdin 
Anthomorpha Bornemann 
Protopharetra radiata do. 
Altaicyathus ; Vologdin 
Claruscyathus do. 
Loculicyathus do. 
Retecyathus do. 
Sibiricyathus ` : do. 
Family Metacoscinidae, Bedíord, 1936. EN 
The genus Metacoscinus Bedford 1934 has “wire 
netting-like’’ septa, and sporadic “tabulae” of peculiar 
type; it grows from an irregular base without central 
cavity and from a spitz of Archaeopharetra type simi- 
Jar to that figured in Plate XXX, Fig. 123. Two very 
similar species: occur at the Ajax Mine, ‚one, a fine 
meshed species with 2 mm. intervallum, is (Archaeo- 
cyathus) retesepta Taylor, the other, with coarse mesh 
' and 5 mm. intervallum is Metacoscinus reteseptatum 
Bedford. - Another species with very dense outer wall, 
thrown. into irregular bulges, is Metacoscinus insigne 
Bedford. ۱ ; ۱ 
Besides this genus we have found at the Ajax Mine 
a few scarce and rather puzzling specimens of which 
` the tabulae are strongly arched, but otherwise resemble 
78 
those of Coscinocyathus, whilst the base is of irregular 
structure and there are other anomalous features not 
usually met with in Coscinocyathus. ‘These fragments 
were described in our second paper, p.: 18, as Para- 
coscinus mirabile and are placed provisionally in the 
family- Metacoscinidae, f ; 
Fragments of another very remarkable type Pycnoi- 
docoscinus pycnoideum Bedtord have strongly arched | 
tabulae, and the outer wall is thrown into langes, re- 
sembung those of Pycroidocyathus. Details, alike of 
both walls and tabulae, differ widely from those of ` 
Coscinocyathus. The base and spitz of this striking 
but very rare species have not yet been found. It is 
placed provisionally in the family Metacoscinidae. 
New Family Flndersicyathidae. 
Members of the family appear to grow from an 
irregular base or spitz of Archaeopharetra type. ‘The 
most characteristic feature of the upper part is the inner 
wall, consisting of large canals directed inwards and 
upwards, into the central cavity. The septal structures 
present a remarkable evolutionary series passing from 
species with an unusually oriented trabecular mesh 
through those with more or less waved septa to others 
with straight well defined ‘septa. Details of many 
species are given in our former papers and in Taylor's — 
monograph. All the species are relatively scarce and _ 
specimens are usually much obscured by secondary 
silicification; it is exceptionally difficult to find a clear. 
and well defined spitz. The small spitz shown in Plate 
XXIX, Fig. 120A, is almost certainly one belonging to- 
this family, and the larger spitz of a coarse-structured 
species shown in Plate L, Fig. 205, shows transition | 
from the Archaeopharetra-type base to the inwardly 
directed inner-wall-canals and trabecular septal mesh” 
in the upper part. (Compare Flindersicyathus rete). 
Genus Flindersicyathus, Bedford. 
The genus was proposed on p. 28 of our fourth 
memoir and details given there and in previous pages. 
It is characterised by an intervallar tissue of curved. - 
lattices and an inner wall with large canals leading 
upwards and inwards into the central cavity. 
Flindersicyathus decipiens, Bedford, may be taken as 
genolype. Other South Australian species are (Spiro- 
cyathus! irregularis and radiatus and (Pycnoido- — 
cyathus) ptychophragma and (Protopharetra) rete — 
Taylor and Flindersicyathus circliporus, tabulatus and 
macdonnelli and (Spirocyathus) multifidus, major and 
speciosus Bedford. 
Genus Pycnoidocyathus, Taylor. a 
Taylor's definition of the genus is “cups in which 
the outer wall is thrown into deep horizontal bulges. | 
Usually synapticulate. Septa within the peripheral - 
bulges highly irregular.” The first species he describes, 
"which may be taken as the genotype, is Pycnoidocyathus ... 
synapticulosus. We wish to redefine the genus as "cups - 
