TRANSACTIONS OF THE SECTIONS. 59 
On aremarkable Phenomenon presented by the Fossils in the Freshwater Ter- 
tiary of the Island of Cos. By Professor E. Forsss and Lieut. Spratt, R.N. 
In the island of Cos there is an extensive deposit of freshwater tertiary strata, ap- 
parently agreeing in age with the freshwater tertiaries of Lycia, which the authors had 
shown to be of an age subsequent to the miocene, and certainly of older date than the 
newer pliocene period, as these freshwater beds are anterior to and form the uncon- 
formable walls of a well-defined marine formation, containing numerous newer plio- 
cene fossils, In the freshwater strata are found abundant and well-preserved shells 
of the genera Paludina, Neritina, Melanopsis, Melania, Valvataand Unio. Examples 
of the first three of these genera are most numerous, and are found throughout the 
"vertical extent of the formation, distributed in three successive series of horizons, 
a 
pal 
In each of these horizons is a species of Paludina and of Neritina, and in each of the 
two lower ones are two species of Melanopsis. The lowermost species of each genus 
are smooth, those of the centre partially plicated, and those of the upper part 
strongly and regularly ribbed. The forms of the examples of these several genera 
in the several zones are so very distinct and well-marked, that at first examination it 
would appear that each series of horizons was characterized by a Paludina, Neritina 
and Melanopsis of its own and representative of each other. If the species are re- 
garded as distinct, either such conclusion must be come to, involving the supposition 
of a succession of creations and extinctions during the (geologically) short period in 
which the lake existed, or a transmutation of species must be maintained. 
The authors propose the following solution of this geological problem without 
having recourse to such extreme suppositions. In the uppermost part of these beds 
there is evidence of the influx of the sea converting the fresh into brackish water. 
The Cardium edule occurs there. Finding that the smooth shells of several existing 
mollusca under such conditions become distorted and plicated, they are inclined to 
refer the appearances described to such a cause, and to regard these three Paluding 
as one species: so also with the other genera. Referring to the facts made known 
by Mr. Forbes, that races of mollusca cannot remain for more than a limited time 
on the same horizontal area, though they may reappear when the ground is suffi- 
ciently changed, (their embryos, which have been swimming free under a rudimentary 
and pterupodous state, in the meantime developing themselves on the new ground,) 
the authors hold that, by the time the ground was renewed for the development of 
the progeny, of the lowermost of the Paludine for instance, the composition of the 
water had changed so far as to affect, though not destroy, their form during their 
development; and that this was again and still more the case when the germs of 
_ the middle Paludine, &c. assumed the last form under which the several species 
appeared, 
Abstract of a Paper on the Physico-Geographical Description of Mount Etna. 
By Baron von WALTERSHAUSEN. 
Baron von Waltershausen began his researches in the year 1835, accompanied by 
_ Professor Listing of Gottingen, and continued them on his second journey during the 
years 1838 to 1843 with M. Peters of Flensburg and M. Cavallari of Palermo. 
_ The fruits of his labours are in the course of being published under the title, ‘ The 
_ Etna and its Revolutions.’ A large atlas will accompany this work, with an intro-~ 
duction written both in German and French. The principal object will be to give 
an exact representation of the mathematical, physical and geographical relations of 
Mount Etna, including an accurate historical survey of all the different eruptions, 
beginning from the earliest times up to the year 1843, The atlas, engraved by M, 
Cavallari, of which the first section has just been published, will contain a topogra- 
phical and geological map of this volcano on the scale of 1 in 50,000, besides a large 
number of views, sections and other interesting details: The author hopes to be 
able to give a complete theory of the formation of the mountain and the revolutions 
it has undergone in the course of time, and to have arrived, by comparison with other 
voleanoes of Southern Europe (Vesuvius, the Liparian Islands), to results applicable 
to voleanoes in general. It may, perhaps, be stated that in this work, which the 
author considers as the principal labour of his life, the first attempt will be made to 
put the observation of geological phanomena on a mathematical foundation, 
