Geological Society of London. 89 
A revision of the type specimens of the three species included by 
Mr. Billings in the genus Archcocyathus shows that each of the 
species represents a distinct genus. Archeocyathus profundus, having 
been selected by Mr. Billings in 1865 as the typical species, was 
retained as such, and the characters of the genus, as shown in this 
species, were defined; Arch. atlanticus, Bill., was made the type of 
a new genus, Spirocyathus; and the third species, Arch. minga- 
nensis, which proves to be a siliceous sponge, was included in a 
new genus, Archeoscyphia. 
Including the genera allied to Archeocyathus, described by Meek 
and Bornemann, the following constitute the family ArcHmooyYa- 
THIN, proposed by this last-named author; Archeocyathus, Bill. ; 
Ethmophyllum, Meek; Coscinocyathus, Born. ; Anthomorpha, Born. ; 
Protophareta, Born. ; and Spirocyathus, g.n. 
The genera of this family are characterized for the most part by 
turbinate or subcylindrical forms with stout walls enclosing an 
interior tubular or cup-shaped cavity. Their skeletons are of car- 
bonate of lime in a minutely granular condition. The walls in the 
first four of the above-named genera consist of an outer and inner 
lamina connected by vertical and radial septa; dissepiments are 
generally present between the septa; save in the genus Anthomorpha, 
the outer lamina of the wall is regularly and minutely perforate, 
and the inner lamina and septa are likewise cribriform ; Ethmophyllum 
is particularly distinguished by oblique canals connecting the 
interspaces of the wall with the central cavity, Coscinocyathus by 
transverse, perforate tabule, and Anthomorpha by the apparently 
imperforate character of the surface lamine and septa. Protophareta 
and Spirocyathus are either non-septate, or very obscurely septate ; 
their skeleton consists of anastomosing lamine and fibres ; in the 
latter genus the lamine are remarkably thickened by successive 
secondary deposits of calcareous material. 
The Archzocyathine are regarded as a special family of the 
-Zoantharia sclerodermata, in some features allied to the group of 
perforate corals. The family is restricted, so far as is known at 
present, to the lowest fossiliferous zone of the Cambrian strata, that 
characterized by the genus Olenella, Hall, and it occurs at Anse-au- 
loup, Labrador; Troy, New York State; Nevada; in the Sierra 
Morena, Spain; and in the south-west of the Island of Sardinia. 
The genus Archgoscyphia, based on Archeocyathus minganensis, 
Bill., is shown to be a lithistid sponge, and Mipterella, g.n., based 
on Calathium (?) paradoxicum, Bill., belongs likewise to the same 
group of sponges. The genera Calathium, Bill., and Trichospongia, 
Bill., are also undoubted siliceous sponges. These various sponges, 
which were either included in Archeocyathus by Mr. Billings, or 
regarded as allied thereto, have no relation whatever to the genus, 
or to any member of the family in which it is included. They come 
from a higher geological horizon, the Calciferous formation of the 
Canadian geologists, which is probably the summit of the Cambrian. 
They occur in the Mingan Islands and in Newfoundland. Archao- 
scyphia and Calathium are present in the Durness limestones. 
