(1847.| LYELL ON THE NUMMULITE LIMESTONE OF ALABAMA. II 
(Quart. Journ. Geol. Soc. vol. ii. p. 409, May 1846.) At the 
time that my first communication was written, I had not finished my 
explorings in Alabama, nor visited St. Stephen’s Bluff on the Tom- 
becbee river, where I afterwards obtained additional proofs of the 
order of superposition above indicated; nor had I then compared the 
Eocene strata at Vicksburg with those of Jackson in the State of 
Mississippi, which throw light on the same question of relative posi- 
tion. Before adverting to these last-mentioned localities, I will first 
offer a few observations on the country between Claiborne and Clarks- 
ville, for I understand that doubts have been lately thrown on the 
correctness of the views which I have expressed relatively to the true 
age and place in the series to be assigned to the “ rotten limestone of 
Alabama,” and the associated rock in which the fossil first named 
Nummulites Mantelli by Morton abounds*. 
Before restating the grounds of my former opinion and corroborating 
them with fresh proofs, it may be well to say something of the nature 
and zoological relations of the discoid bodies from Alabama which have 
passed under the name of Nummulites, and which constitute the chief 
part in bulk of considerable masses of limestone im certain districts. 
Having obtained many specimens both from Alabama and from 
Vicksburg in Mississippi, in which the structure of this fossil was 
beautifully preserved, I first showed them to Prof. K. Forbes, who at 
once pronounced them not to be Nummulites, but related to some 
living plants or zoophytes which Mr. Jukes had brought from Au- 
stralia. Mr. Lonsdale, who examined them immediately afterwards, 
said, ‘“‘ They are certainly not Nummulites, but allied to some of the 
bodies usually termed Orbitolites, and are, I believe, corals, in the 
usual acceptation of that word.’ Afterwards Mr. Forbes having 
compared the American fossil with the living species from Australia, 
and satisfied himself of its near affinity, sent me the following note, 
dated June 14th, 1847 :— 
<< On the so-called NUMMULITES MANTELLI. 
“The American ‘ Nummulites Mantelli, jadging from Mr. Lyell’s 
specimen, is not a Nummulite, nor is it a foraminiferous shell. It is 
a species of Orbitolites, and consequently a Zoophyte (probably Asci- 
dian). The genus Orditolites was established by Lamarck for the 
reception of a fossil of the Paris basin, the Orditolites complanata, 
which may be regarded as the type. Other tertiary species and a 
Maestricht fossil were associated by Lamarck in the same genus, in 
which he also placed the ‘ Orbitolites marginalis’ of the European 
seas. Respecting the true position of the last-named. body, however, 
there is considerable doubt. 
“The Orbitolites complanata is very nearly allied to the American 
* Sir R. Murchison announced to the Geological Society of London at their 
meeting May 26th, 1847, that he had just received a letter from M. Agassiz, in 
which he stated ‘ that M. Desor had clearly shown that the rotten limestone of 
Alabama was not cretaceous, as Morton and Conrad had supposed, nor Eocene, as 
Lyell had considered it, but was of the age of the Terrain Nummulitique of Bia- 
wiz.” 
