Ch. VI.] 
SICILY-— '-VAL DI NOTO. 
65 
The shells in the limestone are often very indistinct, some- 
times nothing but casts remaining, but in many localities, 
especially where there is a slight intermixture of volcanic sand, 
they are more entire, and, as we have already stated, can almost 
all be identified with recent Mediterranean testacea. Several 
species of the genus Pecten, are exceedingly numerous, par- 
ticularly the large scallop (P. Jacobceus), now so common on 
the coasts of Sicily. The shells which I collected from this 
limestone at Syracuse, Villasmonde, Militello (V. di No to), and 
Girgenti, have been examined by M. Deshayes, and found 
to be all referrible to species now living, with three or four 
exceptions*. 
The mineral characters of this great calcareous formation 
vary considerably in different parts of the island. In the souths 
near the town of Noto, the rock puts on the compactness, 
together with the spheroidal concretionary structure of some of 
the Italian travertins. At the same place, also, it contains the 
leaves of plants and reeds, as if a stream of freshwater, charged 
with carbonate of lime and terrestrial vegetable remains, had 
entered the sea in the neighbourhood. At Spaccaforno, and 
other places in the south of Sicily, a similar compact variety of 
the limestone occurs, where it is for the most part pure white, 
often very thick bedded, and occasionally without any lines of 
stratification. This hard white rock is often four or five hun- 
dred feet in thickness, and appears to contain no fossil shells. 
It has much the appearance of having been precipitated from 
the waters of mineral springs, such as frequently rise up at the 
bottom of the sea in the volcanic regions of the Mediterranean. 
As these springs give out an equal quantity of mineral matter 
at all seasons, they are much more likely to give rise to unstra- 
tified masses, than a river which is swoln and charged with 
* For lists of these see Appendix II. I procured at Villasmonde, seven species ; 
at Militello, ten ; in the limestone of Girgenti, of which the ancient temples are 
built, ten species; from the limestone and subjacent clay at Syracuse, twenty-six 
species; in the limestone and clay near Palermo, also belonging to the newer Pli- 
ocene formation, one hundred shells. 
Vol. III. F 
