Dr. L. Adams on the Geology of the Maltese Islands. 3 
about among the nodules. This variety soon passes into a soft 
pale-coloured freestone, characterized by its disposition to split 
up into fragments: it contains rounded masses and bands of 
chert. The second nodule-bed passes through the centre por- 
tion of the deposit. The nodules are not so large as those 
already mentioned, and present a green colour externally, have 
an earthy fracture, and often contain portions of the fossils 
common to the bed, as if they were hardened portions of clay *. 
Although usually seen in bands of from 1 foot to 18 inches in 
thickness, these nodules may be met with in detached groups or 
strewn irregularly throughout this portion of the bed. The 
third seam of nodules, upwards of 10 feet in thickness, overlies 
the pale-coloured variety. It is the most extensive and fossili- 
ferous of all the nodule-seams, and so loosely bound together 
as often to present the consistence of a gravel. The nodules 
are all more or less rounded, and seldom of large size. Bones 
(chiefly ribs) of Cetaceans are very common. It was in this bed 
that the teeth of the Zeuglodon were first found. A new species 
of Phoca was also lately discovered by the author. Prof. Owen 
has named it P. rugosidens. There are, besides, abundance of 
teeth of upwards of nine species of Squale, including the great- 
toothed shark, Carcharodon megalodon. Single specimens of the 
teeth of this fish have been discovered measuring 6,3, and’7 inches 
at their longest side. As usual, among the Mollusca the Pecten is 
the most common form. Among the Brachiopoda, Terebratulina 
caput-serpentis is sometimes found, and 7. ampulla or T. sinuosa, 
Brocchi; but neither are by any means common in any portion 
of the Caleareous Sandstone. Casts of a Pteropod of the genus 
Fyalea, of the size of a small pea, are very common, not only in 
the nodule-beds, but throughout the deposit. The Echinodermata 
are well represented by abundant remains of species belonging 
to Hemiaster, Schizaster, Spatangus, &e., all which have been 
described by Dr. Thomas Wright, F.G.S.+ 
The pale-coloured variety of the Calcareous Sandstone is the 
most extensive portion of that bed: it is overlain by a reddish 
fawn-coloured sort, with a fourth nodule-bed about halfway. 
The same fossils are met with, including two beautiful Scalarie. 
Nodules of iron in the form of peroxide, or, what are more com- 
mon, hollow masses containing a coating of sulphur, are strewn 
in abundance throughout this portion of the deposit. The 
average thickness of the Calcareous Sandstone is fully 200 feet. 
It forms the surface-rock of nearly one-half of Malta and the 
south and south-western portions of Gozo. The transition 
* The nodules have not been chemically examined. 
t+ Ann. and Mag, Nat. Hist. ser. 2. vol. xv. 
1* 
