32 
There has been much difference of opinion as to the validity of the genus Diphyphyllum 
of Lonsdale, chiefly arising from the fact that its original founder erroneously made its sup- 
posed fissiparous mode of division, a generic character, Milne Edwards and Haime, how- 
ever, pointed out that the mode of increase in the corals referred here is truly by gemmation, 
and not by fission. Hence, they refused to accept the genus, and placed the corals previously 
referred here under Cyathophyllum and Lithostrotion. Upon the whole, however, there can be 
little hesitation in adopting the view advocated by Mr. Billings, (Can. Journal, new series, 
Vol. IV. p. 134,) and in retaining Diphyphyllum as a distinct genus. 
Diphyphyllum, as above defined, differs from Cyathophyllum in its distinctly bi-areal 
structure, the septa not extending to the centre, as they do in the latter genus, nor being 
twisted together, so as to produce the appearance of a small columella, 
From Lithostrotion, which it closely resembles in most respects, Diphyphyllum is separated 
by the invariable absence of a columella. Milne Edwards and Haime, (‘‘ British Fossil Corals,” 
p. 195,) express their opinion that the absence of the columella in Diphyphyllum is accidental 
and due to the process of fossilisation. As pointed out by Mr. Billings, however, there can be 
no question as to the incorrectness of this opinion, the columella being entirely wanting in the 
most beautifully preserved examples of Diphyphylium. 
From Amplexus, Diphyphyllum is separated by the general form of the coral, by the 
greater development of the septa, and by the absence of a septal fossule. 
In all essential points of their structure the genera Hridophyllum and Diphyphyllwm are 
identical, the sole difference of importance being that the corallites in the former genus are 
united to one another laterally by horizontal root-like prolongations of the epitheca. It must. 
be admitted, however, that specimens of Diphyphylium occasionally exhibit similar connecting 
processes, though these are never developed to any extent, and can only be detected by a care- 
ful examination. 
The characters of the genus Diplophyllum (Pal. N. Y., Vol. IL. p. 115),founded by Hall 
for the reception of a common coral from the Niagara Limestone, do not appear to differ 
essentially from those of Diphyphyllum, except that the outer vesicular layer in the former is 
stated to be separated from the central tabulate area by a distinct murai investment. It is 
probable, however, that Mr. Billings is correct in uniting the two genera, 
Two species of Diphyphyllum have been described by Mr. Billings from the Corniferous. 
Limestone of Western Ontario, being amongst the most conspicuous corals of the formation. 
T have also detected specimens inseparable from D. gracile of McCoy, if indeed the latter is. 
not truly identical with D. straminewm (Billings). 
26. DipHYPHYLLUM ARUNDINACEUM (Billings). 
(Plate VI. Fig. 1.) 
Diphyphyllum arundinaceum (Billings), Canadian Journal, New Series, Vol. IV, p. 134.. 
“Corallum forming large masses of long cylindrical straight or flexuous stems, from 
three to four lines in diameter, but usually distant from one to three lines from each other ; 
radiating septa thin, betwen forty and fifty in number, rarely reaching the centre; transverse 
diaphragms turning downwards on approaching the margin; two to four in one line. In some 
of the corallites the walls are so thin and closely united that no separation can be observed, but 
in others of the same cluster an outer area is distinttly visible. There is usually a circular 
space in the centre of the corallites, into which the radiating septa do not penetrate ; often 
however they reach the centre. The young corallites sometimes spring from the sides 
of the parent with a slender base, and curving upwards immediately become parallel with those 
of the whole group. In large colonies frequent instances may be seen, where, instead of this 
lateral budding, a bifurcation takes place, both branches being of the same size. In large 
groups, owing to the numerous additions of young, the corallites diverge slightly, asif radiat- 
ing from a point. The colonies are from six inches to several feet in diameter, and large 
blocks of stone are of frequent occurrence, which are penetrated at right angles to the stratifi- 
cation by the closely crowded stems ” (Billings). 
Diphyphyllum arundinaceum (Billings) is distinguished from the following species 
chiefly by the almost uniformly greater size of the corallites, which average three or four lines 
in diameter when fully grown. In shape the corallites are cylindrical, with annulations and. 
