(Fig. 98 (E)). Septal pores are in about four rows 
(Fig. 98 (C)). Tabulae are straight and rather remote, 
4 or 5 mm. apart, and have numerous pores, about 5 to 
the mm. (Fig. 98 (B)). - 
Sigmocoscinus is certainly a distinct type from 
Sigmocyathus, differing from the latter genus not only by 
its possession of definite tabulae, but also in the finer 
scale of the outer wall structure, the narrower inter- 
vallum, and the nature of the septal pores. | Taylor's 
description and figures of “Coscinocyathus” didymo- 
teichus appear to correspond to our Sigmocyathus and 
not to Sigmocoscinus. 
Order ARCHAEOCYATHINA (Okulitch). 
New Family BRONCHOCY ATHIDAE. 
New Genus Bronchocyathus. 
The genus Bronchocyathus is proposed to include 
certain forms from the Ajax Mine which have previously 
been placed in the genera Archaeocyathus, Ethmophyllun: 
and Coscinocyathus, but which appear to have sufficient 
resemblance to one another to justify reclassification. 
The characteristic features are growth from a normal 
spitz, the presence of extremely numerous thin and 
straight septa, a very finely porous outer wall, inner-wall- 
pores quadrately arranged with a single vertical row oí 
pores to each intersept, the presence of horizontal 
annular shelves projecting into the central cavity and 
their tendency to be produced into teeth, collars, or 
trabecular or vesicular masses within the central cavity, 
and the spasmodic presence of tabula-like structures. 
Taylor’s species (Archaeocyathus) trachealis is the geno- 
type. For figures, photographs, and descriptions of this, 
the commonest of the Ajax species, the reader is referred 
to Taylor’s memoir, and we add a few details not noticed 
by him. We have found two distinct varieties of outer- 
wall-pores in Bronchocyathus trachealis. In one, for 
which we propose the name “variety tectus,” the pores are 
5 to the millimeter in two alternating rows in each inter- 
sept, and each pore is seen (under favorable conditions) 
to be covered externally by a small hemispherical cap 
with a minute aperture at its lower part; (compare 
‚ Coscinocyathus papillipora (Bedford) ( : see Fig. 102, 
Plate XXVI. In the other, Bronchocyathus trachealis 
var. partitus, the pores are much smaller, 10 to the 
millimeter, and arranged in a regular quadrate pattern; 
see Fig. 101, Plate XXVI. The septal pores are difficult 
to find as a rule, but a particularly fortunate etching is 
shown in Fig. 99 (A), in which it is seen that about 12 
vertical rows of minute pores are present, about 4. to the 
mm. in each row. The two innermost rows constantly 
slope upwards and inwards towards the inner wall and 
the pores are here less numerous; across the septa the 
pores are arranged in wavy lines, giving a “watered silk” 
appearance. Peculiar horizontal tabula-like structures 
are occasionally present; most specimens show none at 
all, others.show one or several at varied distances. The 
“tabula” is formed by all the septa giving off a series of 
studs exactly in the one horizontal plane; most of these 
25 
studs just fail to meet those of neighboring septa, 
although they correspond exactly in position, but some 
of them link up; these “tabulae” are shown in Fig 99 
(B). (C). Bronchocyathus grows from a spitz which 
even at a level only two mm. in diameter shows a central 
cavity and the characteristic annular shelves on the inner 
surface of the inner wall; but a certain number of 
specimens show a mass of interlacing tubercles which 
fill the cavity of the lower part of the specimen even as 
high as a level in which the external diameter attains 12 
mm. or more. Presumably this is a later ingrowth from 
the inner wall, and arises in older specimens; see Fig. 
100 (A), Plate XXVI. 
In the same genus, Bronchocyathus, may be placed 
(Ethmophyllum) dentatum (Taylor) and (Archaeocya- 
thus) tracheodentatus (Bedford). Both of these species 
have fine-pored outer walls, which, in the specimens we 
have seen, appear intermediate between the two varieties 
of Bronchocyathus trachealis just referred to; the pores 
are in three alternating rows to the intersept and about 
7 to the mm. The septa in both these species are equally 
close, straight, and numerous with those of B. trachealis. 
In both dentatus and tracheodentatus the specimens 
showing septal pores show a single row only, close to 
the outer wall (see Fig 104 ). This feature 
appears different from the description we have just given 
of B. trachealis, but a specimen of the latter has been 
noticed with the single row of septal pores, and probably . 
there is a tendency in all three species for the inner rows 
of septal pores to become obliterated. The shelves in 
B. dentatus and tracheodentatus are decidedly further 
apart (23 to the mm.) than those in В. trachealis. For 
comparison of the three species see Figs. 100 (B), 103. 
and 104, which are drawn on the same scale of x 12. 
New Species Bronchocyathus sigmoideus.. 
The species is founded on a well-preserved fragment 
which is figured in Plate XXVI, Fig. 105. The specimen 
is tubular conical, about 20 mm. long by 5 mm. diameter 
at the upper end; intervallum coefficient 14 mm.: 2 mm. 
As in other species of the genus, the outer wall pores are 
minute; they are about 8 to the mm., arranged in about 
three alternating rows to each intersept. The septa, as 
in the other species, are straight, thin, and very numerous, 
about. 1/3 mm. apart; septal pores have not yet been 
seen. Near the top of the figure is shown a row oí 
swellings on the septa which recall the “tabula”-like 
structures found occasionally in Bronchocyathus 
trachealis. The inner wall shows an interesting de- 
velopment of the B. trachealis type; near the spitz annular 
bars are present, about 4 to the mm., between which are 
the wall-pores, one to each intersept; as the upper 
portion of the specimen is approached the rings are 
farther apart, and finally are spaced one to the mm., and 
each ring becomes produced to form an annular 
sigmoidally-curved plate projecting upwards and inwards 
into the central cavity. 
Bronchocyathus sigmoideus corresponds very closely 
