508 J. H. Cooke — Globigerina Limestones of Malta* 



vertebras of Stereodon Melitensis, a fish having sauroid dentition, 

 were found. 1 Leith Adams obtained ear-bones, caudal vertebrae, 

 and a penultimate molar of Halitherium 2 ', and in the Valetta 

 Museum are several large vertebrae of Zeuglodon that, judging 

 from the limestone matrix on them, were also obtained from 

 this bed. 



Division I: the fourth nodtde seam. — The fourth or lowest seam 

 of phosphatic nodules averages three feet in thickness, and ranges 

 from two to four feet. The nodules are irregular in shape, and 

 generally present an exceedingly wrinkled and coriaceous 

 appearance. Nearly all of them contain one or more fossil 

 organisms, around which the phosphate of lime has segregated ; 

 and in many cases they consist almost entirely of the shells of 

 foraminifera. Phosphatized remains of molluscs, corals, and 

 echinoderms, the teeth and vertebrae of sharks, bones of whales, 

 and immense quantities of casts and pseudomorphed tests of 

 pteropods, Vaginella and Eyalea, enter largely into the composition 

 of the seam. Alluding to the origin of these nodules, Dr. John 

 Murray 3 points out that they are precisely similar to the phosphatic 

 nodules that were dredged from modern sea-beds during the voyage 

 of the " Challenger," and he is of opinion that these nodules, like 

 their modern pi'ototypes, were formed in situ at the bottom of the 

 Oligocene sea. A sample of rock from this seam was sent to 

 Professor J. P. Blake for analysis and report. The following was 

 the result : — 



Sulphate of lime 1"97 



Carbonate of lime ... ... ... ... 51 - 12 



Phosphate of lime ... ... ... ... 31-66 



Alumina 10-55 



Silica 3-83 



Moisture "87 



100-00 



Conclusion. — The foregoing details afford evidences as to the 

 nature of the bathymetric conditions that prevailed when these 

 strata were deposited. These conditions have already been indicated 

 by Dr. John Murray i and Dr. J. W. Gregory, 5 and I shall therefore 

 now confine myself to a brief summary of the conclusions which the 

 details in this paper seem to corroborate. 



The Globigerina Limestones of the Maltese Islands are broadly 

 divisible into three sections — 



I. The lowest beds, comprising the subdivision I and the lower 



1 Cooke, J. H., "Notes on Stereodon Melitensis, Owen": Geol. Mag., 

 Dec. Ill, Vol. VIII, December, 1891, p. 546. 



2 Adams, A. L., " On the Discovery of the Remains of Halitherium'''' : Q.J.G.S., 

 vol. xxii, p. 595. 



3 Murray, Dr. J., "The Maltese Islands, with special reference to their 

 Geological'Structure " : Scot. Geog. Mag., vol. vi, p. 449. 



i Vide ante. 



5 Gregory, J. "W., "The Maltese Echiuoidea, etc.": Trans. Roy. Soc. Edin., 

 vol. xxxvi, p. 585. 



