also separate this form from 
S. granulata, in which the 
oscula are remote, and can often 
not be detected at all, though 
in other respects the surface- 
characters of the two species 
are identical. The under sur- 
face of S. perforata is still un- 
_known; but the fossil forms 
=) thinner or thicker crusts, often 
covering pretty extensive sur- 
faces; the thicker expansions 
being composed of a succession 
of crusts superimposed one up- 
on the other. 
Fig. 3.—a. A fragment of Stromatopora perforata, showing the 
osculiferous upper surface, natural size ; b. fragment of the same, Locality and F ormation.— 
magnified to show the internal structure ; c. vertical section, Rare in the Corniferous lime- 
showing the form and course of the canals. stone of Port Colborne. 
4, STROMATOPORA GRANULATA (Nicholson). 
Plate I., Figs. 3 and 3 a. 
Stromatopora granulata (Nicholson), Annals and Magazine of Natural History, August, 
1873, Plate LV., Figs. 3 and 3 a. 
Fossil forming thin crusts, or horizontally-spreading expansions (usually about a quarter 
of an inch in thickness, but ranging from one line up to half an inch), often occupying ex- 
tensive surfaces. Crust composed of concentric calcareous laminze, from six to ten in the space 
of one line, separated by interspaces which are minutely broken up into cells by numerous 
delicate vertical rods. Upper surface regularly undulating, often raised into chimney-like or 
conical elevations, which are for the most part destitute of : any appearance of being perforated, 
but which are sometimes pierced by distinct rounded apertures or “ oscula.” The entire sur- 
face is covered with a fine miliary granulation, constituted by minute conical pustules, placed 
close together, often confluent and arranged in sinuous lines, and apparently imperforate. One 
example, however, shows that this granulated layer is not the true surface, but that it was 
covered in the perfect organism by an exceedingly delicate calcareous membrane, perforated 
with minute apertures or “e pores.” Exfoliated and broken specimens show that similar ora- 
nulated surfaces occur at small intervals all through the mass. The under surface (in some 
cases at any rate, is supported upon a concentrically-wrinkled calcareous basis, precisely 
similar to the epitheea of a Favosites or a Fistulipora. 
The specimens upon which I founded my original description (Loe. cit. p. 94) did not 
exhibit some of the most important of the points comprised i in the foregoing specific diagnosis. 
In none of the examples which at first came under my notice, was “T able to detect either 
oscula or pores. In a fragment, however, of this species, which T discovered in the Hamilton 
formation of Widder. I have now succeeded in detecting both these structures; and I have 
obtained additional examples from the Corniferous formation, showing the under surface and 
also the mode of growth. 
S. granulata is, so far as at present known, one of the few species of Stromatopora in 
which two sets of apertures exist, one large and exhalant, the other small and inhalant. In 
the specimen from the Hamilton ‘shales in which these apertures can be detected, the oscula 
have the form of comparatively large openings, of a circular or oval shape, placed at the sum- 
mit of distinct rounded or conical elevations. The pores, on the other hand, are only observ- 
able in a portion of the specimen, and are seen to have the form of minute close-set perfora- 
tions in a delicate caleareous membrane or layer. Beneath this layer, and over all parts of 
the fossil where it has been denuded, is seen the ordinary granulated surface from which the 
name of the species was originally derived. There is thus a stropvg probability established 
that all the specimens from the Corniferous limestone, which exhibit simply this granulated 
surface are imperfect, and that there has been removed from them an exterior and very deli- 
