Miscellaneous. 353 
most perfect oval. The bones of the hind feet are proportionably 
longer, although less strong; lastly, its form is much more slender 
than that of the other Anourous Batracians, and may belong as well 
to the Frogs properly so called as to the Tree- frogs (Hyla), which 
differ from the former only in the extremity of each of their toes, 
which is enlarged and rounded into a kind of viscous swelling. But, 
as may be imagined, this character has not been preserved. The 
Rana aquensis has preserved a portion of its skin; there is scarcely 
any part but the feet which has been deprived of it, and these are 
represented by the bones which form their skeleton. As may be 
judged by its dimensions, this fossil frog is small, and its form is far 
from corresponding to the idea which we may form of the tertiary 
fauna of Aix, if we imagine it among the palm-trees, the crocodiles 
and other animals which have left their remains in the gypsiferous 
marls. 
It is well known, that when the discovery of a diurnal lepidopterous 
insect in the same formation was announced to the Entomological So- 
ciety of Paris, M. Boisduval, one of the most celebrated entomologists 
in Europe, considered the fact as so novel, that he would not credit it 
until he had examined the specimen. As this discovery has passed, 
we may say, unnoticed, I shall be pardoned for entering into some 
details on the almost miraculous occurrence which enabled M. Bois- 
duval not only to recognise the genus to which this butterfly be- 
longed, but also to determine its species with the greatest ease. As the 
opinion of this naturalist perfectly agrees with the ideas which I have 
previously entertained and published on the probable temperature of 
the globe at the period of the deposit of the gypsums of Aix, I can- 
not resist supporting my opinion by such an authority, especially as 
M. de Serres (Géognosie des Terrains Tertiaires, p. 220, &c.) states 
that the genera of fossil insects of that locality are mostly identical 
with those which now inhabit Provence and more southern climates, 
as Sicily and Calabria ; and as M. Boué ( Guide, ii. p. 286) says that 
it is well-known that the fossil plants and fishes of Aix are most nearly 
related to the vegetables and marine fishes of Provence, whilst it has 
been proved that the gypsiferous marls of Aix are essentially of a la- 
custrine origin, and that no maritime plant or animal has ever been 
discovered there. Mr. Curtis (Edinburgh New Phil. Journal, Oct. 
1829) in the same manner refers all the specimens from Aix to still 
existing forms. Now as the gypsums of Aix are inferior to the ma- 
rine molasses of the central beds, containing animals the greater part 
of whose genera only live in the tropical regions, the occurrence in 
a lower stratum of species still existing in the country or in the ad- 
joining countries, established a fact of anomalous distribution, and a 
contradiction, not only to almost all known facts, but also to the 
presence in the same stratum of crocodiles, palm-trees, and other 
species of warm climates. We must therefore consider the conclu- 
sions advanced by the naturalists whom we have cited as the result 
of erroneous determinations, into which the specialty of M. Boisdu- 
val has prevented his falling. That entomologist discovers, ‘ that 
the most common species of insects of the gypsiferous beds of Aix 
Ann. & Mag. N. Hist. Vol. xvi. 2¢ 
