A2 PERMIAN FOSSILS. 
Hlasmopora is nearly related to Hschara in the position of the cellules relatively to 
the plane of the frond, and in the structure of the same parts; but it differs from the 
latter in the fronds beimg perforated, and composed of only one plate of cellules. 
Reverting to Phyllopora ; this genus differs from Fenestella, Polypora, and Synocladha, 
in its fronds not being formed of radiating or parallel stems or ribs ; from the first two, 
in the want of non-celluliferous connecting bars; and from the first and the last,! in the 
nearly vertical position of its cellules in relation to the plane of the fronds ; while the 
plain-margined cell-apertures of all these genera, and the bi-structural character of 
their fronds, consisting on the one side of cellules or polypidoms, and on the other of 
capillary tubes, seem strongly to favour their intimate alliance, and their belonging to 
one and the same family. 
With regard to Hasmopora, there is an unapproachable difference between it and 
Pihyllopora, as will be seen by placing collaterally the principal characters of each. 
Phyllopora, (vide Pl. V, figs. 3, 4, 6.) Hlasmopora. 
Outer or under surface or side of the fronds cellu- Inner or upper surface or side of the fronds cellu- 
liferous. liferous. 
Fronds composed of two lamine of different struc- Fronds composed of one lamina consisting simply 
tures. Inner lamina of capillary tubes (fig. 4 a, of cellules or polypidoms. 
and fig. 6 6); outer lamina of cellules or polypidoms 
placed nearly at right angles to the latter (fig. 3 6, 
and fig. 6 a). 
Substance of celluliferous side consists of cellule- Substance of celluliferous side consists of the front 
wall of the cellules. 
Cellules nearly parallel to the plane of the fronds. 
interstices or dissepiments (fig. 3 ¢, and fig. 6 c¢). 
Cellules nearly at right angles to the plane of the 
fronds. 
Cellule-apertures parallel to the plane of the 
fronds. 
Margin of the apertures plain. 
Cellule-apertures more or less at right angles to 
the plane of the fronds. 
Margin of the apertures furnished with tubular 
and other processes. 
I suspect that Phyllopora will eventually embrace several species of Paleozoic 
Corals; but until more is known of their structure, it seems preferable to wait rather 
than make generic identifications which may eventually prove incorrect. Is the so- 
called Retepora prisca, represented in Phillips’s ‘ Palaeozoic Fossils,’ pl. xii, fig. 37, 
furnished with cellules on the outer surface? Perhaps I may be permitted to request 
a close examination of the curious fossil M‘Coy has described in Dr. Griffith’s 
‘Synopsis,’ under the name of Refepora undata (pl. xxix, fig. 11), with the view of 
ascertaining whether or not it belongs to this genus. 
1 Being unacquainted with the internal structure of Polypora, I cannot speak as to the position of its 
cellules. 
