368 ORTMANN — DISTRIBUTION OB 1 DECAPODS [Aprils, 



Strait of Bengal} The only connection of Africa during these 

 times was with South America, the old Archiplata (Jurassic and 

 Lower Cretaceous) and the old Archiguiana (Archhelenis, Upper 

 Cretaceous). On the southern margin of the Tethys, as sketched 

 above, there is a zone in the desert region of North Africa and 

 Arabia, where Jurassic deposits are wanting and Cretaceous directly 

 overlies Paleozoic beds. This indicates a farther extension of 

 Afiica northward in Jurassic times and a transgression of the sea 

 southward in the Cretaceous (Neumayr, 1890, p. 386). The 

 deposits of the Cretaceous sea can be traced very distinctly in a 

 broad belt from Syria over Arabia, Persia, Afghanistan and Beluch- 

 istan to Northern India. 



Also in the Older Tertiary (Neumayr, p. 480) the Central Medi- 

 terranean Sea reaches from the Atlantic Ocean to India, and it was 

 not until after the end of the Oligocene that its unity was de- 

 stroyed. In the beginning of the Miocene Western Asia became 

 largely land, and thus a broad connection was established from 

 Asia to Africa (India to Arabia), and at the same time from Asia 

 to Europe, which was then forming (Neumayr, 1890, p. 501 f.). 



In detail the processes in the northeastern part of Africa were the 

 following : Arabia during Mesozoic and the greater part of Tertiary 

 times was broadly connected with Africa. The Red Sea did not 

 exist, according to the unanimous opinion of all writers (Neumayr, 

 Suess, Gregory, Blankenhorn and others). The origin of the Red 

 Sea falls late in Tertiary times, after the connection of Africa with 

 India was long established, and thus, in the second half of the 

 Tertiary, a regular exchange of the faunas of Africa and India 

 could take place, for which we possess ample evidence. 



The Red Sea is a rift valley, which is tectonically connected 

 with the valley of the Jordan river in Palestine. 2 The most de- 

 tailed investigations on this question have been published by 

 Blankenhorn. 3 According to this author, the Mediterranean Sea 

 (the western part of the old Tethys) in Miocene times sent a wide 

 bay to the southeast, which extended as far as the southern end of 

 the Gulf of Suez, which, of course, did not then exist, and the Nile 



1 Which, however, was temporarily interrupted during the Upper Cretaceous. 

 See above, p. 330. 



1 See Gregory, J. W., in Proc. Zool. Soc. London, 1894, p. 165. 

 3 Blankenhorn, M., in Centralbl. f. Mineral., etc., 1900, p. 209 ft'. 



