112° 
of considerable size. Both sides of the polyzoary carry cells, but the cells which open upon 
one aspect are separated from those which open on the other side by a thin concentrically-stri- 
ated laminar axis or membrane, precisely similar to the axis of Ptilodictya. In the elathr- 
ate species the margins of the apertures are surrounded by a strong striated non-celluli- 
ferous border, 
There can be no doubt asto the very closerelationship between Clathroporaand Piilodictya ; 
and it may reasonably be doubted if the former can be retained apart from the latter. One 
of the chief characters of Ptilodictya is the presence of a thin striated membranous axis be- 
tween the two series of cells on the two aspects of the coencecium. No such character appears 
to have been observed by Hall in Clathropora, or is alluded to in his description of this genus, 
and its absence would certainly be a sufficient ground for generic distinction. I have, how- 
ever, determined the existence of a laminar axis exactly similar to that of Ptilodictya, both 
in a Corniferous species of Clathropora and in C. frondosa (Hall), from the Niagara Lime- 
stone, the type-species of the genus. The striated non-celluliferous margins of Ptilodictya 
are also represented by precisely similar margins surrounding the fenestrae in both C. frondosa 
(Hall), and in C. énterteata (Nich.) It would appear, therefore, that the chief difference be- 
tween Olathropora and Ptilodictya is to be found in the fact that the cells of the latter are 
arranged in rows separated by distinct elevated lines, which certainly appears not to be the 
case in the typical species of the former, though the contrary is asserted by Hall. The mode 
of growth of Clathropora in itself clearly does not afford sufficient ground for generic distinc- 
tion, and the more or less quadrangular form of the cell-mouths is certainly only an occa- 
sional phenomenon in the type-form C. frondosa. Upon the whole, therefore, whilst retain- 
ing Clathropora in deference to the opinion of such a high authority as Prof. Hall, I am 
inclined to believe that the forms included under it may safely be placed under Ptilodictya. 
The following species is the only one which has come under my notice as occurring in 
the Devonian Rocks of Western Ontario. 
135. CLATHROPORA INTERTEXTA (Nicholson). 
Clathropora intertexta (Nicholson), Geological Magazine, March, 1874. 
Polyzoary forming a thin flattened expansion, composed of broad branches which inoseu 
late so closely as to leave simply rounded or oval apertures or fenestra perforating the frond. 
The width of the branches is from a line to a line and a half; and the fenestrae are oval or 
circular in shape, about a line and a half or a little more in diameter, and placed at intervals 
of about a line or a line anda half. The margins of the fenestree are surrounded by a striated 
non-celluliferous zone. The frond is celluliferous on both sides, forming two continuous layers, 
their proximal ends or bases being placed back to back, but separated by a delicate calcareous 
membrane or laminar axis, which exhibits numerous close-set transverse curved strie, From 
six to ten cells occupy the space of a line measured diagonally, whilst the form of the cell- 
mouths is oval or circular, and the cells do not appear to be arranged in distinct lines sepa- 
rated by elevated striz. 
of Clathropora intertexta (Nich.) is closely allied 
to C. frondosa, a beautiful and not very rare spe- 
cies in the Niagara Limestone. In the latter 
| species, however in all the specimens that I have 
| examined, whil t the width of the branches is 
much about the same as in C. inétertexta, the in- 
 osculation is so effected as to leave very much 
; smaller fenestrae which have a diameter of only 
s§ about half’ a lin , and which look simply like little 
aad oval or circular perforations in the membranous 
Clathropora intertexta stata She a, Portion of; the 5 nila eave nee Ae at a pe re 
frond, natural size ; b. Fragment of the same, enlarged the sho figured by Hall (Pal. N. Y., Vol. 
shewa Portion of the central ‘membranous ‘axis’ From JT) Pl X1L., B., fig. 65.); but, another example 
figured by the same (Loc. cit., fig. 5a.), has much 
larger fenestrules, about the same in size as in (©. intertexta, though more elliptical. ‘This, 
however, can not be considered as belonging to the same species as Fig. 5)., with the smaller 
fenestrae ; and as all the specimens I have seen, however large, agree with the characters of 
