352 Miscellaneous. 
a longer time to grind down the irregularities of the surface, which 
is best effected by rubbing them upon a piece of wet unpolished 
marble. 
For the deeper cells Mr. Thwaites finds nothing so good as marine 
glue, which must be melted and dropped on the slip of glass, like 
sealing-wax, then warmed and flattened with a piece of wet glass: 
what is superfluous must be cut away with a knife, so as to leave 
only the wall of the cell; should this become loose, it ean easily be 
fixed by heating the other side of the slip of glass over a spirit-lamp 
and gently pressing. Before these cells are used, it is desirable to 
flatten them by rubbing gently upon a piece of wood and then upon 
the wet marble. 
In using the cells, as small a quantity as possible of gold-size, 
of a thick consistence, should be laid on the wall of the cell, and also 
on the edge of the piece of thin glass ; and in covering up the cells, 
gentle pressure should be employed in order to squeeze out the su- 
perfluous fluid. 
It would be a very useful thing for travellers to take with them 
the proper ingredients for preparing the two solutions for fresh and 
marine algee. A portion of each species of alga might then be pre- 
served in small phials carefully sealed and ticketed, which may be 
mounted and observed at leisure. The benefit of such a practice has 
been strongly impressed upon me during the examination of some 
highly curious foreign alge which have lost many of their distinctive 
characters in drying. M. J. BerKELey. 
On the Discovery of a Fossil Frog and Butterfly in the Gypsum Deposits 
of Air. By M. Coquann. 
Among the fossils in my possession from the gypsum formation of 
Aix, a remarkable and very distinct impression of a reptile belonging 
to the order of the Batracians, and to the family Anoure, has par- 
ticularly caught my attention: M. Boué (Guide du Géol. vol. ii. 
p. 259) notices indeed, in the tertiary formations, the presence of 
some reptiles, such as salamanders, frogs and ophidians ; but as 
he does not enter into any details, either of their description or the 
localities in which they have been found, the palzontologist will 
perhaps read with interest some details respecting the species in my 
possession. Its dimensions are as follows :— 
Millimetres Millimetres 
Total length of the body, inclu- Cubitus and radius ...........0606 
dune the Weg oo escossstess 32 truncated in part...sc2sci2e.& 
Great diameter of the head ... 13 | Femur ............ devcumaseeee donee 
Transversal diameter ...scc..sees Srl SED a cee ns aacceat Siaecaa heeeaSe agit 9) 
Diameter of the sternum at the TATSUSieswoscsessa nate eee 7 
origin of the anterior feet .... 9 | Toe of the posterior foot ......... 5 
Length of the humerus ......... 6 
The body of this species, which I shall name Rana aquensis, is not 
so plump as that of the common frog; its head, although as flat, is 
more elongated, and is terminated by a snout which describes an al- 
