278 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 25, 



extension in the northern regions during the palaeozoic period ; and 

 the valuable researches of Mr. Darwin have also revealed to us that 

 the existing conditions of some portions of the southern hemisphere 

 at the same aera were favourable to the development of other spe- 

 cies of the family Brachiopoda nearly related to those which in 

 Northern Europe characterise the rocks of the palaeozoic aera. 



EXPLANATION OF THE PLATES. 

 Plate X. 

 Fig. 1. Orthis SuUvani, sp. n. 



a. Ventral valve, exterior. 



b. Dorsal valve, exterior. 



c. Ventral valve, interior. 



d. Dorsal valve, interior. 

 2. Orthis concinna, sp. n. 



a. Dorsal valve, exterior. 



b. Dorsal valve, interior. 

 Z, Airypa palmata, sip. n, 



a. Ventral valve, exterior. 



b. Dorsal valve, exterior. 



c. Dorsal valve, interior. 



d. Ventral valve, interior. 



4. Chonetes Falklandica, sp. n. 



a. Ventral valve, exterior. 



b. Dorsal valve, interior. 



c. Ditto, ditto. 



5, Orbicula (undetermined). 



Plate XL 

 Fig. 1. Spirifer Hawkinsii, sp. n. 



a. Ventral valve, exterior. 



b. Dorsal valve, interior. 



2. Spirifer antarcticus, sp. n. 



a. Ventral valve, exterior. 



b. Dorsal valve, interior. 



3. Spirifer Orbignii, sp. n. 



a. Dorsal valve, interior. 



b. Ventral valve, interior. 



c. Dorsal valve, exterior. 



4. Orthis tenuis, sp. n. 



a. Ventral valve, exterior. 



b. Dorsal valve, interior. 



3. Notice on the Coal-Fields o/* Alabama ; being an extract from 

 a Letter to the President jTrom Charles Lyell, Esq., F.R.S., 

 dated Tuscaloosa, Alabama, 1 5th February 1846. 



Since my arrival in Alabama I have devoted part of my time to the 

 investigation of the carboniferous rocks, and have obtained informa- 

 tion respecting some coal-fields, the very existence of which in this 

 State was unknown to me in 1844, when I compiled the Map of the 

 Geology of the United States, published in my ' Travels.' On my way 

 southwards, I had learnt from several persons in Georgia that the 

 city of Mobile was supplied with bituminous coal, brought down the 



