. 97 
Se 
do not know of any Paleozoic forms of Polyzoa with which this could be compared, and it 
is readily separated from such forms as Defrancia by the entirely different characters of the 
cells, which approach closely in form to those of Retepora, Polypora, and Fenestella. The 
largest group that I have seen comprises about twenty of the discoid coencecia, mostly in 
contact but apparently in no way connected with one another directly. : 
Locality and Formation.—Hamilton Group, Bartlett’s Mills, near Arkona, Bosanquet. 
118. CERIoPoRA (?) HAMILTONENSIS (Nicholson). 
Ceriopora (?) Hamiltonensis (Nicholson), Geological Magazine, April, 1874. 
Polyzoary ramose ; branches cylindrical, about half a line in diameter, dividing dicho- 
tomously at intervals of from a line and a half to three lines, the angle included between 
each pair of brauches being about 40° or 45°. * Surface covered with oval, rounded, or sub- 
‘quadrate cell-mouths, arranged in longitudinal rows, which are separated by delicate thread- 
like lines. The cells of each row alternate with those of the next row, so that they come to 
be disposed in regular diagonal lines. About four rows (sometimes five) occupy the width of 
the stems, the cells having a width of about a tenth of a line; and there are about five cells 
in the space of one line, measured vertically. The interspaces between the mouths of the 
cells are occupied by exceedingly minute tubuli, which form only a single row or are altogether 
absent on the lines which bound the cells laterally, whilst they usually form a double series 
on the spaces by which the cells of a given row are separated vertically. 
This beautiful little fossil occurs in great abundance in some of the 
beds of the Hamilton Formation. It is allied to the Ceriopora punctata of 
Goldfuss (Petre. Germ. Pl. LXIV., Fig. 12,) and to Millepora interporosa, 
(Phillips, Geol. of Yorkshire, Vol. I1., Plate I., Figs. 36-39), especially to 
the former, but it is distinguished from both by perfectly good and 
easily recognized characters. I am, at present, unable to decide as to its 
seabaidh Bedwas og SERS generic affinities, and have simply referred it provisionally to Cerio- 
Ceriopora (2) Hamilto- pora on account of its close relationship to C. punctata, (Goldf.) which 
nensis (Nich.) natural ]ikewise occurs in the Devonian Rocks. 
size, showing the mode of i f ; 5 Ms 
branching. @ a fragment Locality and Formation.—Common in the Hamilton Formation, 
of the same. enlarged to Widder, Township of Bosanquet. 
cells and ‘the tubular in- 
tercellular interspaces.— e 
From the Hamilton group 
Fig. 33. 
Genus PriLopicTYA (Lonsdale), 
“ Corallum thin, calcareous, foliaceous, or branching dichotomously ; branches sometimes 
coalescing ; a thin, laminar, flattened, concentrically wrinkled central axis, set with oblique 
short sub-tubular or ovate eells on both sides, with prominent oval mouths nearly as large as 
the cells within ; branches often flattened, with the margin solid, sharp-edged, striated, and 
without ce!ls; the boundary ridges of the cel!s square or rhomboidal ” (McCoy). 
The genus Pfilodictya of Lonsdale is identical with Sfictopora of Hall, and includes a 
group of curious Polyzoa, which are essentially Silurian, but which extend into the Devonian 
Rocks, and appear even to have survived into the Carboniferous period. The presence of a 
non-celluliferous striated margin does not appear to be absolutely essential or to be universally 
present in the genus; and the central laminar axis or septum, which separates the cells of 
opposite sides, is sometimes longitudinally striated, as well as being concentrically wrinkled. 
A single species of the genus, which I cannot identify with any previously recorded species, 
occurs plentifully in the Corniferous Limestone, and more rarely in the Hamilton formation 
of Western Ontario. 
119. Prizopicrya MexKi (Nicholson). 
Ptilodictya Meeki (Nicholson), Geological Magazine, March, 1874. 
Polyzoary having the form of thin, very much flattened elliptical branches, which have 
an average width of about a line, rarely reaching a line and a half or two lines, with a thick- 
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