654 REPORT — 1902. 



had evidently occupied a portion of the Atlantic had any connection with 

 America. Wollaston, too, who had a most intimate knowledge of the Atlantic 

 Islands, strongly supported the view that their fauna reached them across dry 

 land. 



Imhued, however, with the idea of the permanence of the great ocean basins, 

 Wallace vigorously attacked one and all of these theories, and contended that 

 there was not only no connection between Europe and America across the 

 Atlantic, but that the fauna of the Atlantic Islands was derived from the adjoining 

 continents of Europe and Africa by winds and marine currents. The weight of 

 the arguments brought forward by Wallace silenced all critics for a time, and the 

 influence of his views is traceable in most of the more recent writings on the 

 subject. But, since some leading geologists have expressed themselves against 

 the theory of the permanence of the great ocean basins, the older views of a 

 possible land-connection between Europe and the Atlantic Islands, and also 

 between Europe and America, are again discussed. I have therefore collected 

 together a number of facts regarding the distribution of animals which had not 

 hitherto been utilised, in order to make a renewed attempt from a zoological point 

 of view to solve the Atlantis problem. 



The results of my investigations tend to show that Madeira and the Azores 

 are the remains of an ancient tertiary area of land which was joined to Europe, 

 and that it probably became disconnected in Miocene times. Since then this land 

 once more became united with our continent, and may not have been finally 

 severed until the Pleistocene period. As regards the question of a land-bridge 

 across the Atlantic, many reasons can be given in favour of such a theory. It 

 must, however, have occupied a position farther south than the land just alluded 

 to. Uniting North Africa with Brazil and Guiana in early tertiary times it 

 probably subsided during the Miocene period, leaving only a few isolated peaks 

 as islands in the midst of the vast ocean which has since replaced it. 



2. Diagram of the Skull of Mastodon angustidens. 

 By Dr. C. W. Andrews, B.A., F.G.S., F.Z.S. 



The especial interest of the diagram exhibited lies in the fact that it corrects 

 thoselfigures of M, anf/ustidens previously published, notably that by Professor 

 Gaudry, which shows the tusks curving upwards like those of an ordinary elephant. 

 The downward direction of the tuslvs in this early proboscidean is particularly 

 interesting as being a primitive character derived from the early ancestral form 

 Mw7-itheriuvi, lately discovered by the author in Egypt. In this it is clear that 

 the tusks are merely an enlarged pair of second incisors, and there seems no 

 reason to doubt that in Palceomastodon, Mastodoii, and the later elephants the 

 upper tusks are homologous with those teeth. 



Another remarkable character of the early mastodons is the immensely elon- 

 gated mandibular symphysis, which is prolonged far beyond the upper jaw, and bears 

 a pair of procumbent incisors which terminate in a chisel-like worn surface. Con- 

 sidering that they project far in front of the upper jaw, and lie between the widely 

 divergent upper tusks, it is difficult to see what they worked against unless it was 

 a hard suriace on the ventral face of the proboscis. 



3. The Breaking-up of Coral Rock by Organisms in the Tropics.^ 

 By J. Stanley Gardiner, M.A. 



The problem is mainly of interest from the bearing that it has on the forma- 

 tion of the lagoons of atolls out of flat surface reefs. There are two classes of 

 animals — those which bore into coral or coral rock and break it down into small 



' A full account of the action of boring and sand-feeding organisms will be 

 found in The Fauna and Geography of the Maldive and Laccadive Archipelagoes, 

 Camb. Univ. Press, vol. i., pt. 3, pp. 333-341 (October 1902). 



