Mr. Lyell on the Coal Field of Tuscaloosa, Ala. 371 
plates, but also from their peculiar form, together with the poste- 
rior position of the arch-like structure on the inferior surface, we 
propose for it the name Macropetalicthys rapheidolabis, in allu- 
sion to the great size of the scutcheon plates, and the pincer-like 
form produced by the union of their sutures. 
This is so far as we know, not only the first instance of finding 
scutcheoned fishes in this country, but, also, the lowest position 
in which remains of Vertebrata have been found, if we except 
defensive fin bones, which occur in New York nearly in the same 
geological position, viz. in the corniferous group, and the scales 
of fishes which the Professors Rogers traced throughout the Clin- 
ton group of Pennsylvania and Virginia. 
Madison, Ia., Feb. 16, 1846. 
Note by D. D. Owwen.—Some of the members of the Academy 
of Sciences in Cincinnati, supposing it to be a Pterichthys, sug- 
gested the name P. N orwoodensis out of compliment to Dr. Nor- 
wood, who secured the specimen and first called the attention of 
men of science in the West to it. Dr. N. as well as myself, ob- 
jects to this principle of nomenclature superseding the descrip- 
tive one ; it is for this reason alone that I have consented to this 
decision. 
Arr. IV.—Coal Field of Tuscaloosa, Alabama,—being an ex- 
tract of a letter to Prof. Stuuman, from Cuarves Lyetr, Esq., 
dated Mobile, Alabama, Feb. 19th, 1846. : 
Since I wrote to you last, I have been engaged in the study 
of the carboniferous rocks and coal of Alabama, respecting the 
existence and extent of which, I was unable to obtain any accurate 
- information, when I compiled the small geological map of the 
United States that accompanied my Travels. Mr. Conrad had 
mentioned to me the existence of a bed of coal, the geological 
age of which he had not ascertained, above Tuscaloosa, and I 
learnt from several persons on my way south, as I passed through 
otgia; that the city of Mobile was supplied with bituminous 
coal, for fuel and gas, brought down the 'Tombecbee River, by a 
navigation of more than 350 miles. When I heard that it was 
procured not far from. the northern outcrop of the newer forma- 
tions, whether cretaceous or tertiary, that it occurred very near 
