Microscopic Structure of the Teeth of the Lepidoste. 359 
ter Mr. Lyell finds the same fossils as those of Windsor, &c. before 
mentioned. Near Sydney these gypsiferous strata pass beneath 
aformation of sandstone more than two thousand feet thick, 
upon which rest conformably the coal-measures of Sydney, dip- 
ping to the northeast or seaward, and having a thickness of two 
thousand feet. — 
To illustrate the gypsiferous formation the author gives a par- 
ticular description of the cliffs bordering the Schubenacadie for a 
distance of fourteen miles from its mouth to Fort Ellis, which he 
examined in company with Mr. J. W. Dawson and Mr. Duncan. 
The rocks here consist in great part of soft red marls, with sub- 
ordinate masses of crystalline gypsum and marine limestones ; also 
three large masses of red sandstone, coal-grits, and shales. The 
strike of the beds, like that at Windsor, is nearly east and west, 
and there are numerous faults and flexures. ‘The principal mass- 
es of gypsum do not appear to fill rents, but form regular parts: 
of the stratified series, sometimes alternating with limestone and 
shale. ae se : sap 
- The author concludes by describing a newer and unconform- 
able red sandstone, without fossils, which is seen to rest on the 
edges of the carboniferous strata on the Salmon River, six miles 
above Truro. pores 
Arr. XIIL—On the Microscopic Structure of the Teeth of the 
- Lepidostei, and their Analogies with those of the Labyrintho- 
_donts ; by Jurrrres Wyman, M. D.—(with a plate.) 
[Read before the Boston Society of Natural History, August, 1843.] 
Tur Lepidostei, like other Sauroid fishes, are provided with 
large conical teeth, intermixed with more numerous teeth of a 
smaller size. ‘The larger teeth are found on the upper and lower 
maxillaries, and the intermaxillaries ; the smaller ones are found 
on the same bones, and also on the vomer and palatines. On the 
two last they are arranged “en carde,” except on the anterior 
portion of the vomer in the Lepidosteus oryurus, where they are 
arranged in a linear series. The larger teeth, of which the mi- — 
croscopie structure is here more particularly described, are a little — 
recurved, have a conical form, and sharp and slightly trenchant 
points; externally the surface js smooth near the apex, but more. 
