J. H. Cooke — Globigerina Limestones of Malta. 505 



crustaceans, corallines, fish, and cetaceans. Tfc has an average 

 thickness of about 18 inches, and it is very uniform in its general 

 physical and chemical aspects. The interstitial cement contains 

 about 2 per cent, of phosphoric anhydride, all of which is found in 

 combination with iron, alumina, or lime. These nodules contain 

 a much higher percentage of alumina and of iron than do the 

 nodules of seam iv. 



The following analysis shows the composition of the nodules of 

 this seam : — 



Carbonate of lime (Ca C0 3 ) 40-24 



Sulphate of lime(CaS0 4 ) 1*55 



Phosphate of lime (Ca 3 2 P0 4 ) 39-52 



Phosphates of iron and alumina 6-50 



Eesidue 1200 



99-81 



The interstitial cement is of a very soft nature and readily 

 disintegrates. The nodules and fossils therefore drop out in con- 

 siderable quantities along the bases of the valley escarpments, and, 

 becoming incorporated with the soil, they render it highly fertile 

 and productive. Many of the fossils are of a jet-black colour, 

 due to the substitution of the pre-existing phosphate of lime for 

 phosphate of iron by the decomposition of bicarbonate of iron. 1 

 Pecten denudatus, P. Pandora, and P. varians occur; Scalaria refusa- 

 ls common ; but S. Ducei is rare. Among the echinoderms Brissopis 

 crescenticus, Schizaster Parkinsoni, and Brissus latus are common. 

 Pteropods and large-sized Foraminifera, chiefly Grhtellaria and 

 Nodosaria, are enormously prevalent, as well as the teeth of Telostean 

 and other fish, and the rib-bones and vertebra? of Cetaceans. 



Division E. — This bed is fully developed in nearly every portion 

 of the two islands, and it is, therefore, the most conspicuous strati- 

 graphical member of the series. In colour it varies from blue to 

 a pale ashen-gray, and it has an average thickness of about 40 feet. 

 It is traversed at different levels by two thin seams of phosphatio 

 nodules ; but though of frequent occurrence they are only locally 

 developed. They commence and break off very abruptly. At 

 Maddalena, near the northern extremity of the Great Fault, three 

 of these seams are shown, the uppermost of which is very pockety 

 and disappears in an easterly direction, while to the westward it 

 thins out and breaks off abruptly. The remaining two may be 

 traced for 50 yards to the east, when they, too, break off abruptly. 

 Thin mounted sections of the rock show them to be made up 

 almost entirely of the tests of minute foraminifera, among which 

 Globigerinee predominate. The corals and the Scalaria; now become 

 very rare ; and pelagic mollusca and other forms characteristic of 

 deep waters take their place. Terehratula sinuosa, Balantium, and 

 Vaginrtla depressa occur at this horizon. I obtained two specimens 

 of Aturia aturii (British Museum Collection) from the middle of 



1 Bicarbonate of iron would be formed by the reaction of iron-oxide, and carbonic- 

 oxide derived from decaying organic matter. 



