PROF. P. M. DUNCAN ON STREPTELASMA RG@MERI. 167 
8. On SrrerrenasMA Rameri, @ NEw Corat from the WeEntock 
Sane. By Prof. P. Marin Duncan, M.B. (Lond.), F.R.S., 
V.-P. Geol. Soc. (Read January 24, 1883.) 
[Puate VII.] 
VurY numerous specimens of simple Corals belonging to the Rugosa 
were found in the washed Wenlock Shale prepared by G. Maw, Esq., 
F.G.S. Amongst them are forms which have not hitherto been 
described, but which are allied to a species from Girvan. They 
belong to the genus Strcptelasma, Hall, and are specifically distinct 
from any others. As the variability of some parts of these Corals is 
great, and there are some interesting points abont their morphology, 
I have brought them before the Society in this communication. 
STREPTELASMA Ramenrti, sp. nov. Plate VII. figs. J-18. 
The corallum is simple, free, reversely conical in shape, slightly 
bent and horn-like, sharp at the base, longer than broad, and with a 
circular or elliptical calicular margin. 
The calice is widely open, shallow, and has a central depression 
leading to a more or less distinct fossula. About fifty costs cover 
the corallum, and they are subequal in breadth, slightly rounded, 
and separated by linear depressions. Their length differs according 
to their position and direction, and there are four sets of them: 
three on the convex side of the bent corallum and partly on the 
flanks, and one on the concave side and partly on the flanks 
(figs. 4, 5, 6). 
Of the three sets on the convex side,,one is composed of two 
coste: placed side by side, and reaching from the base to the calice 
in a vertical line. ‘They are usually slightly larger than the other 
cost, and are very distinct and parallel (fig. 5). There is another 
set on either side of these. Each of these sets consists of ten 
costz, which pass obliquely from the outer edge of the vertical pair 
upwards and outwards, and reach in succession the calicular margin 
(fig. 4). The longest costee leave the vertical pair close to the base, 
and the shortest close to the calice, and the others at intermediate 
distances. The result is a pinnate arrangement. 
The shortest coste, and three, four, or five that follow, are deci- 
dedly oblique in their direction ; but the longest, which are of course 
found at about a quadrant of the calicular circle from the vertical 
pair, are barely oblique; their direction is nearly vertical, and 
they reach the base. 
The fourth set of costee is on the concave side of the bend of the 
corallum and on the flanks (fig. 6); it is more numerous than the 
others combined, and the direction is not identical. The longest costz 
of this set are opposite the vertical pair on the other side of the 
corallum, and reach from calice to base, but they are not very if 
at all distinct from the others of this set, except in their vertical 
