101 
Locality and Formation.—Rare in the Hamilton group, Bartlett’s Mills, Arkona, Township 
of Bosanquet. 
Genus RetErora (Lamarck). 
Polyzoary forming a reticulated expansion composed of flexuous inosculating branches, 
‘which are not united by distinct dissepiments, but which anastomose in such a manner that 
the entire frond forms a continuous network perforated by regular apertures or fenestrules, 
In the funnel-shaped species the cells are placed on the upper or inner surface of the ccenc- 
cium, and there are two or more rows of cells to each branch. Outer surface striated. 
The genus Retepora is separated from Polypora by the fact that the fenestrules are 
formed simply by the coalescence of the flexuous branches at definite points, and thus look 
like perforations in the ccencecium, whereas in the latter the fenestrules are formed by a dis- 
tinct series of non-poriferous dissepiments. From Fenestella, Relepora is separated by not 
possessing dissepiments and by the common occurrence of more than two rows of cells to each 
branch, In the funnel-shaped species of /etepora the cells certainly usually occupy the inter- 
nal face of the funnel, whereas they are generally external in those species of Fenestella which 
have the same shape. I should be inclined to doubt, however, if this character is universal, 
and it certainly cannot often be used as a practical means of distinguishing the species of 
these two genera, since its application fails in the case of fragments of the infundibuliform 
species, and also of the fan-shaped forms. 
’ The following species of Refepora occur in the Devonian Rocks of Western Ontario. 
124, Rerepora PRIscA (Goldfuss), 
* — Retepora prisca (Goldfuss), Petref. Germ. Pl. XXXVL, fig. 19. 
Retepora prisca (Phillips), Pal. Foss. Cornwall, &c., p. 25, fig. 37. 
Fenestella prisca (McCoy), Pal. Foss., p. 76. 
Polyzoary forming broad, fan-shaped, or undulating expansious, which in some instances 
have the form of an open funnel. Branches parallel, flexuous, and undulating, alternately 
and recularly bent from side to side, the stccessive convexities and concavities on each side of 
each branch being opposed to corresponding convexities and concavities in the branches im- 
mediately contiguous, actual anastomosis taking place at the successive points where two 
convexities meet, so that the entire frond becomes perforated by a series of oval apertures or 
‘fenestrules.” Branches about one-third of a line in width, eight or nine in a quarter of an 
inch measured transversely, furnished with a strong but blunt keel on the non-celluliferous 
side, so that their backs are angulated, Reverse, when well-preserved, finely striated. Fen- 
estrules regularly alternate in contiguous rows, and thus arranged in diagonal lines, broad- 
oval or diamond-shaped, half a line in length and rather less in width, three in the space of 
two lines measured diagonally, and the same number in a quarter of an inch measured verti- 
eally. Fenestrules separated vertically by interspaces of about half a line, along which the 
branches are coalescent. Cells carried in the funnel-shaped examples on the inner or upper 
surface of the coeneecium ; two rows of cells to each branch, alternately arranged, and those 
opposite the points where the branches unite larger than the others. Four or five cells to the 
length of a fenestrule. 
I have no doubt as to the identity of this abundant 
species with the familiar Retepora prisca of the Conti- 
nent of Europe and Great Britain. The only point in 
he 
i\ 
i 2% which our species appears to differ from £. prisca is in 
is Sage Wh the angulation (for it is this, rather than a true carina- 
ee? af tion) of the non-cellular face of the branches. This 
i Meade Be feature, however, is only shown in very well preserved 
ee specimens, and is absent in others, and I do not think 
6 it is one of such importance as to justify the formation 
Fig. 38. of a new species. { do not comprehend upon what 
Pee Rete ere) (Gpldnuss), grounds McCoy shculd have placed this species under 
-celluliferous face, enlarged. 0b. Fy ; ° : 5 . 
Fragment of the same from which the striatea /enestella, since its reference to Retepora is rendered in- 
outer layer has been removed. showing the backs ite istl i ie 
of the cells, enlarged. From the Corniferous Lime~ dubitable by the marked absence of distinct dissepi 
stone, ments, and by the fact that the fenestrules are formed 
simply by the coalescence of the flexuous and regularly undulated branches. 
Locality and Formation.—Common in the Corniferous Limestone of Ridgeway and Port 
