In length it is about 8; inches, and 4 in breadth. The dorsal fin, reaches from the middle of the back to the tail.
From Humbleton quarry, situated mile from Bishop Wearmouth, on the road to Durham, I have received the following specimens, imbedded in hard buff-coloured crystalline limestone.
1. Caste of the internal part of the vertebral column of the Cap Encrinite. See Parkinson, vol. 2. tab. 10. fig. 4.
2. A species of Dona: with hair-like spines.
3. Casts of reticulated Alcyonite. Parkinson, vol. 2. tab. 10. fig. I, 2, 3.
4. Smooth shelled bivalves, from the sine of a pen to that of a cockle, resembling those of the genus Donax.
5. Small round bodies, delineated by Parkinson, vol. 2. tab. 8. fig. 10.
6. Casts of bivalves, resembling muscles.
7. Casts of Arcæ and Anomiæ. Sowerby, Brit. Min. tab. 55.
8. Impressions of a reticulated marine production resembling the genus Flustra.
III. Coal Measures.
The coal-seams and the rocky strata which together constitute the coal-formation of Newcastle and Sunderland, are in part covered by the magnesian limestone, and rest upon the lead-mine measures. They occupy a hollow, or trough, of which the extreme length from the Alklington colliery, near the Coquet, in the north, to Cockfield, in the neighbourhood of West-Auckland, is 58 miles; and the breadth, from Bywill on the Tyne, to the sea-shore, is 24 miles. This formation first makes its appearance on the south bank of the
