REPORT ON THE DIATOMACE/E. 1 5 



far as the right bank of the Savio above Ccsena, and on the other as far as the hills which 

 flank the valley of the Misa above Sinigaglia. It also occurs at the extremity of the 

 peninsula in the province of Catanzaro. 



The microscopic examination of the Diatoms contained in these deposits warrants the 

 conclusion that they belong to the same formation and constitute so many tracts of the 

 same bank, which, though as yet imperfectly known in all its parts, probably extends over 

 the whole of Italy from Sicily to the vicinity of the most ancient Jurassic formation of 

 the Alps. 



It may perhaps prove to be an interesting problem for the geologist who possesses a 

 knowledge of the palaBontology and stratigraphy of the lands which surround the basins of 

 the Mediterranean and Adriatic Seas, to compare this marine tripoli with the diatomaceous 

 deposits of the Antarctic, and to endeavour to determine the directions of tertiary oceanic 

 movements, and compare them with those now prevailing in the Southern hemisphere. 



In opposition to the hypothesis that has just been advanced, it is to be noted that 

 Mr Murray is of opinion that the great Antarctic diatomaceous bank is but a portion of 

 a much more extensive formation which girds the Antarctic Pole. 1 I believe, however, 

 that sufficient proof of the existence of this belt has not yet been obtained, and that 

 should it exist the circumstances that bring about such a formation would remain to be 

 determined. It is true, indeed, that Sir Joseph D. Hooker, during the expedition of the 

 "Erebus" and "Terror," discovered, between the parallels of 76° and 78° S. lat., a 

 bank of Diatoms 400 miles in length and 120 miles in breadth, but such a discovery 

 cannot be regarded as sufficient to prove the uninterrupted extension of the deposit 

 around the Antarctic Pole. The bank found by the Challenger naturalists did not extend 

 beyond 60° 26' S. lat., and was succeeded by a deposit of blue mud, which, however, con- 

 tained many Diatoms, and may be continuous with that observed by Sir J. D. Hooker. 

 Finally, it may be noted that should such a singular diatomaceous annulus gird the South 

 Pole its counterpart might be expected in the Arctic Sea. Yet, although this area has 

 been much more explored than the Antarctic, and although it is much less deep, so that 

 dead frustules might much more readily reach its bottom, no such ring-like deposit has 

 been discovered. Mr Murray points out that this is probably to be accounted for by 

 the Diatoms being much less numerous in the surface waters, and by the fact that their 

 presence would be almost completely masked by the great abundance of terrestrial debris 

 in all the deposits of the Arctic Ocean. 



1 Loc. cit., p 541. 



