19 
7. BLOTHROPHYLLUM DECORTICATUM (Billings). 
(Plate IV., Fig. 3.) 
Blothrophyllum decorticatum (Billings) : Canadian Journal, New Series, Vol. IV., p. 130, 
Fig. 25. ° 
‘“‘ Adult specimens, two feet in length, and three inches in diameter ; dimensions of the 
immature individuals, variable ; usually slender and irregularly curved ; outer area consisting 
of rather strong rudimentary transverse diaphragms, curving upwards and outwards, distant 
from two to eight lines, bearing upon their upper surfaces imperfect radiating septa, which do 
not extend from one diaphragm to another. ‘These septa are half a line distant at the mar- 
gin of a specimen three inches in diameter. When the epitheca is preserved, the surface of 
this species is marked by ‘numerous deep annulations and sharp encircling folds, their edges 
being always on the upper side. The transverse diaphragms in the central area are nearly flat, 
but have a strong septal fossette upon one side” (Billings). 
In the examples which I am disposed to refer to this species, the arched tabule of the 
outer area are not less than two lines apart, often from a quarter to half an inch, and the 
tabulee of the central area are also distant. The central tabulze are often quite flexuous, but 
are never elevated into a boss; most usually they are nearly flat. The septa which spring 
from the upper surface of the arched tabulz of the outer area only reach the tabulee immedi- 
- ately above in the inner portion of the area in question ; butin the outer portion of the same 
area fall far short of the tabulz above, owing to the faet that the tabulee are strongly arched, 
and have their concavities directed towards the base of the coral. The concave under sur- 
faces of the tabulze of the external area present, however, well-marked ridges corresponding 
with the septa on the upper surface. The septa on the upper surfaces of the tabule vary 
from half a line to a line in distance from one another, but there are very generally intereal- 
ated between the larger septa smaller ones, one between each pair, which have simply the form 
of slightly elevated ridges. The epitheca is not only marked with encircling annulations and 
folds of growth, but also with distinct longitudinal grooves, five in the space of two lines, 
The epitheca, however, is rarely preserved, and specimens occur most commonly in one.or 
other of two conditions. Hither the epitheca has been removed, exposing to view the 
arched tabulz of the outer area with the imperfect septa on their upper surfaces ; or the entire 
outer area has been removed along with the epitheca, leaving the central and intermediate 
areas in the form of a core to the outside of which are attached the bases of the arched 
tabule of the outer area. This gives rise to an appearance which is exceedingly characteréstic 
of the present species, and by which it can almost be infallibly recognized even in very imper- 
fect examples. 
Locality and Formation—Common in the Corniferous Limestone of Port Colborne, 
Ridgeway, Hagersville, and at many other points where the formation is exposed. 
8. BLOTHROPHYLLUM APPROXIMATUM (Nicholson). 
(Plate 1V., Fig. 2.) 
Blothrophyllum approximatum (Nicholson), “Canadian Naturalist,” Vol. VIL., No. 3.1873. 
Corallum of unknown length, cylindrical. The outer area consisting of strong arched 
diaphragms, curving upwards and outwards, distant from one another from half a line to 
two lines, bearing upon their upper surface imperfect septa which extend from one tabula to 
another when the tabule are remote by the former distance only, but which do not do so 
otherwise. Septa alternately large and small, distant about a third of aline. Tabule of the 
central area closely approximated, from three to four in the space of two lines, flat or slightly 
flexuous, the septa only slightly encroaching upon them. Epitheca with numerous constric- 
tions of growth and encircling annulations, and obscure longitudinal strive. Dimensions 
unknown, but certainly attaining a diameter of three inches. 
In most of its essential characters this species agrees with Blothrophyllum decorticatum, . 
(Billings, ) of which perhaps it is merely a variety. It is, however, distinguished by its gene- 
rally much greater size and by the apparently constant peculiarity that the tabule of’ the 
outer area are very closely set, much more closely than in B. decorticatum. Thus typical 
. 
