(illiJ) — ON CANADIAN CAVERNS. 
179 
footing, and when in the cave a person can stand upright, with 
plenty of room to spare. The roof is composed of limestone, and 
lined with a coating of stalactitical carbonate of lime, but from which 
there do not project any stalactites ; some portions of the tloor, how- 
ever, contain stalagmites, a few specimens of which were collected. 
No bones of animals were found, possibly owing to the presence of 
the water. Their existence can only be ascertained by pumping the 
water out, which may overlie a sort of breccia. The ridge, which is 
composed of the Trenton limestone, here partakes somewhat of the 
character of a hill, at the base of which is an opening leading into 
the interior of the cavern. It was accidentally discovered some 
thirty years ago on the occasion of a party of hahitans going out 
hunting. The dog belonging to the party c;)mmenced to scratch at 
the spot which forms the entrance, and suddenly disappeared ; the 
animal had fallen into it, and his cries brought the hunters to the 
hole in the ground. The opening was enlarged, and the party 
entered by crawling on their hands and feet. 
From the description of the cavern, it would appear that its origin 
is due to upheaval from below, pi-oducing a dislocation of the stratum 
of limestone and the formation of a wide fissure, which may be found 
ultimately to extend much farther than the distance given in the 
foregoing account. The discovery of this cavern was looked upon 
at the time as something very wonderful. 
(To he continued.) 
THE CARBONIFEROUS SYSTEM IN SCOTLAND CHARAC- 
TERIZED BY ITS BRACHIOPODA. 
By Thomas Davidson, Esq., F.R.S., F.G.S., Hon. Member of 
the Geological Society of Glasgow, etc., etc. 
(Continued from Vol. iii., p. 115._j 
XXXVI. — Productus costatus. Sow. PI. ii., figs. 22-34; pi. iv., fig. 25. 
Producta coduta. J. do C. Sowerby, Mineral Conchology, vol. vi., p. 115j 
pi. dlx., fig. 1, 1827. 
Tiiis species ap])ears to vary somewhat in appearance, but is usually trans- 
versely semi-cvliudrical, the liinge-liue being at the same time the widest 
portion of tlie shell. The ventral valve is very much vaulted, and usually 
lougitudiually divided by a median depression or sinus of variable depth. Tiie 
beak is small, and does not overlie the hiugc-line, while the ears are of moderate 
dimensions and clearly defined. Exteriorly the surface is ornamented with 
numerous longit\idinal ribs, wliieh increase in number by means of occasional 
intercalations ; certain ribs will also disappear before having attained the 
