43 PERMIAN FOSSILS. 



Masmopora is nearly related to JEschara 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 being perforated, and composed of only one plate of cellules. 



Reverting to Phyllopora ; this genus differs from Fenestella, Folypora, and Synocladia, 

 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 Elasmopora, there is an unapproachable difference between it and 

 Thyllopora^ as will be seen by placing collaterally the principal characters of each. 



Phyllopora, (vide PI. V, figs. 3, 4, 6.) Masmopora. 



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 lamince 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 b) ; outer lamina of cellules or polypidoms 

 placed nearly at right angles to the latter (fig. 3 b, 

 and fig. 6 a) . 



Substance of celluHferous side consists of cellule- Substance of ceUuliferous side consists of i^xe front 



interstices or dissepiments (fig. 3 c, and fig. 6 c). y^all of the cellules. 



Cellules nearly at right angles to the plane of the Cellules nearly parallel to the plane of the fronds, 

 fronds. 



Cellule-apertures parallel to the plane of the Cellule-apertures more or less at right angles to 



fronds. the plane of the fronds. 



Margin of the apertures plain. Margin of the apertures furnished with tubular 



and other processes. 



I suspect that Phyllopora will eventually embrace several species of Palaeozoic 

 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 Betepora prisca, represented in Phillips's ' Palaeozoic Fossils,' pi. xiii, 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 Betepora undata (pi. xxix, fig. 1 1), 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. 



