220 
upper margin, or one mucli crumpled, contorted, and curled. Dissepiments and 
interstices but little differentiated (exce]jt by tbe much greater breadth of those 
portions representing the former) , more or less coalescent and the interstices many 
times dichotomous. Peuestrules numerous, oval or round, arranged in regular vertical 
series. Celluliforous surface internal, the dissepiments usually cell-bearing. Basal 
plate thin. Outer surface striate or granular. 
Ohs. The names Femslella and Polypora had been indiscriminately used by 
some Writers for colonies which really possess the characters of Phyllopora, except that 
the cell-bearing face, or aspect of the polyzoarium, was internal instead of external, as 
expressly stated by Professor 'W . King in the case of his genus. It is for these 
infundibuliform and intei’inediate PhyUop)ora-Yi\iQ forms that Professor L. Gr. De 
Koninck has proposed his genus Protoretepora. In a few words it may be said to differ 
from allied genera, as follow's : — Prom Fenestella, by having the whole of one face of 
the polyzoarium cell-bearing, and that the internal instead of either the internal or 
external, and the colls not limited to the interstices only ; from Polypora, by the 
absence of a well-defined separation of ’the polyzoarium into interstices and dissepiments, 
and the whole of the cell-bearing face celluliforous ; lastly, from Phyllopora, simply 
by the fact that the celluliferous aspect is internal, and not external, the arrange- 
ment and disposition of the cells being exactly the same. 
Protoretepora would at first sight appear to have close relations to the recent 
Petepora, and it appears that the only reason assigned for their separation by Professor 
De Koninck scarcely seems sufficient. Pie says that “in Petepora, properly speaking, 
the branches are arranged {contourn&cs') in such a way as to form meshes, and not regular 
rows of ‘ oscules ’ or fcnestrules ” (f.e., as in Protoretepora). 
After examiuing carefully a specimen of the recent Petepora Peaniana (King), 
one cannot see that the difference pointed out by Prof. De Koninck is of sufficient 
importance in itself to base a generic separation on. On the other hand, if we look a 
little more minutely into the subject, we shall find a much more satisfactory reason for 
the separation of the two forms. 
Lonsdale long ago pointed out in describing * his Fenestella ampla, that the 
polyzoarium was bilamellar, the outer layer or back of the branches being “ composed 
of a uniform crust,” upon which are seated the tubular cells, at right angles, or a little 
obliquely to the former, Tliis structure is exceedingly well shown in Mr. Lonsdale s 
figure given in Count Strzolecki’s work,t but wo are indebted for a further and fuller 
exposition of it to Professor W. King. This Author showed J that in his genus 
Phyllopora, and some other Palajozoic genera, the frond was bilamellar or bistructura , 
consisting of a lamina of capillary tubes, called the basal plate, and an outer lamina e 
cellules, arranged more or less at right angles to, and on this. On the other ban , 
he states that in the Elasmoporid® (=lioteporida}, Auct.), the frond is uni-lainel ° 
celluliferous, “ composed of one lamina, consisting simply of cellules orpolypidoms. 
before stated, this bilamellar structure has been shown to exist in Protoretepora amp 
by Lonsdale, and it appears to me a character of much more generic value than 
more arrangement of the feuestrules only. 
The distinction between Fenestella and Protoretepora is even more than a genex 
one, it IS even that of a sub-family. In the former the cells are arranged in reguu 
rows on each side, a prominent keel traversing every branch. In the later genus 
* Darwin’s Deol. Obs. Vole. Islands, pp. 1G3, KM. 
f Phys. Pescrip. N. S. Wales, &c., 1845, t. 9, f. 3(/. 
X Ann. and Mag. Nat. Hist., 1849, pp. 388-90 ; Mon. Perm. Foss. England, 1852, p. 42. 
