12 PROCEEDINGS OF THE GEOLOGICAL Society. [June 9,- 
fossil. The Orbitolites elliptica of Michelin, from near Nice, and 
that author’s Orbitolites Pratti, are also closely allied species. 
“In British strata, species of Oréitolites are recorded from the 
greensand of Milber Down, from the chalk of Lewes and from the 
coralline crag of Sutton. It is possible however that bodies belong- 
ing to distinct genera have been placed together in our lists. 
“Mr. Jukes has collected at Swan River in Australia numerous 
disciform bodies, apparently Ascidian Zoophytes, which occur therein 
great numbers upon marine plants resembling Zostera, and when dead 
are found in great abundance in mud, procured by the dredge from 
various depths under seventeen fathoms. These discs are usually 
about half an inch in diameter and are composed of minute cells. 
They appear to me to belong to the same generic group with the ter- 
tiary Orbitolites, and such appears also to have been the opinion of 
Defrance, for we can scarcely doubt that these are the bodies alluded 
to by him (in the following passage) as living m the seas of New 
Holland: ‘Cette espéce (i. e. Orbitolites complanata of the Paris 
basin) a les plus grands rapports avec celle que Pon trouve...... 
vivant dans les mers de la Nouvelle Hollande.’ (Dict. des Se. Nat. 
t. 36, Art. Orbitolite.) Margmopora of Quoy and Gaimard seems 
to be a similar if not identical body. 
“ As the subject stands at present, then, we have no right to infer 
from the presence of an Orbitolite, however abundant, that the stra- 
tum in which it occurs belongs to one period more than another, 
between the commencement of the cretaceous epoch and our own 
canes =. 
A few days after I had received this communication from Mr. 
Forbes, a letter reached me from M. D’Orbigny, of which I subjoin 
a translation :— 
“© DEAR SIR, “ Paris, 18th June, 1847. 
“‘T have been long acquaimted with the fossil body which you for-. 
warded to me, and at this moment I am printing, in an elementary 
work, all the mistakes concerning it; it is, in fact, of all genera that 
perhaps which has been most often misunderstood, and I should eall 
it the greatest culprit in geology. It is a genus nearly allied to Or- 
bitolina, and which I have named, in consequence of this analogy, 
Orbitoides. It has always been taken for a nummulite, though it | 
differs from it by the most marked characters. 1 have known many 
species, such as the O. media, papyracea, and that which you have for- 
warded to me, and which I had designated by the name of Americana. 
The Orbitoides are found in the cretaceous and tertiary formations, 
the Nummulina in the tertiary only. Such at least is the result of 
my numerous investigations on this subject. The species that you 
have forwarded to me had been sent me from North America, with 
a great number of tertiary and cretaceous shells ; it came to me with- 
out any information respecting it, and I am anxious to know where 
you found it. “Yours, &c., 
“To C. Lyell, Esq.” « Arcrpe D’OrsiGny.” 
* The Plagiostoma dumosum of Morton is decidedly a Spondylus. 
