on the surface by small apertures, and passing more or less vertically through the component 
layers of the mass (Pal. Foss, p. 14 and p. 65). There is some ambiguity in the language 
used by this eminent palzontologist in describing these tubes and their openings in S. con- 
centrica ; and the evidence is not at present sufficient to warrant any positive statement of 
opinion as to whether they may correspond with the “pores’’ or the ‘‘oscula” of an ordi- 
nary sponge. It is probable, however, that they should be regarded as representing the 
‘pores,’ and that the “ oscula” will yet be discovered by a more extended and careful ex- 
amination. Again, in S, ostiolata, (Nich.), a species from the Guelph formation of Canada, the 
upper surface of the mass carries small but regularly arranged openings, which can hardly be 
regarded as being other than “oscula” (Annals of Natural History, Aug., 1873, p. 90, Pl. 4, 
fig. 1). In 8. tuberculata (Nich.), again, I have now discovered a system of comparatively 
large, though remote, openings which communicate with canals traversing the organism, and 
which appear to fulfil beyond all question the function of exhalant apertures. Undoubted 
oscula also occur in S. granulata. Lastly, in the S. perforata (Nich.), now described for the first 
time, the entire mass is perforated by numerous and close-set canals, of considerable size, open- 
ing at the surface in rounded apertures and generally at the summit of chimney-like or coni- 
cal eminences. These openings must represent “oscula.’’ It is true that in few instances 
with which I am acquainted has any species of Stromatopora been shown with certainty to 
possess two sets of apertures, small and large, one set being inhalant and the other exhalant. 
It must be remembered, however, that the difficulties of observation in this case are very great ; 
and the “‘ pores ’’ might have escaped notice either from their minute size, or from the condi- 
tion of mineralisation in which these fossils occur, all the cavities of the mass being filled up 
with foreign matter, and the reticulated tissue itself being often silicified. Or, it is possible 
that in some of these ancient forms the two sets of apertures were of equal size, and are thus 
incapable of being distinguished in a fossil condition. Still there are some cases in which 
fossils in other respects referable to Stromatopora have been shown to possess both inhalant 
and exhalant apertures. The cases in question are S. granulata (Nich.), in a single speci- 
men only ; S. twbulata (Nich.), a still undescribed species from the Niagara limestone of 
Indiana, and S. /indei (Nich.), from the Niagara limestone of Canada. Of this last named 
species, I append an engraving in which these two sets of apertures are well exhibited. 
c. The shape of the various species of 
Stromatopora is such as would accord 
perfectly well with the beliefthat that 
they are Sponges. Some are in the 
form of rounded or irregularly hemi- 
spherical or conical masses. Others 
are somwhat cup-shaped ; and others, 
again, have the form of irregular and 
extended crusts, apparently attached at 
one point to some solid body, from 
which they spread laterally in every 
direction. 
Upon the whole I think the evi- 
dence is very decidedly in favour of 
the view that the genus Stromatopora 
is referable to the Calcispongie. In 
accordance with this view, I shall retain 
in this genus the forms here described 
as S. tuberculata and S. perforata ; since 
these, at any rate, appear to be un- 
questionably sponges, and they would, 
upon any other view of the affinities of 
Fig. 1.—Stromatopora Hindei (Nich.), a, upper surface Stromatopora, requir e a new genus to 
of a fragment, of the natural size; b, vertical section, be formed for their reception. 
enlarged ; c, upper surface of a fragment, enlarged— The genus Stromatopora appears to 
Niagara limestone. h: ia dae am saul 
ave commenced its existence in the 
Lower Silurian and to have died out in the Carboniferous period. In the Devonian period 
the genus would seem to have attained its maximum ; and [ have to record no less than five 
