Hcuglin's " Reise Nach Ahessinien " 153 



the origin of the Btue Nile, for if the Manatee exists in the Tana 

 Sea, and the Bkie Nile issues from the Tana Sea, one would ex- 

 pect that the Manatee should be found in it too. In all maps the 

 Blue Nile is laid down as issuing from that sea; a considerable part 

 of its course, after leaving it, is, however, marked with dots, 

 signifying that it has there not been explored, and is laid down 

 from supposition. There is at least one cataract in this unexplored 

 upper part of the river, which may prevent the Manatee passing 

 into the Nile, although such obstructions are more powerful ob- 

 stacles to the ascent than the descent of river animals. But the 

 reason why the Manatee is not known in the Nile may be that the 

 Blue Nile does not, in reality, flow out of the Tana Sea at all, or 

 rather that the river which does flow out of it is not a tributary of 

 the Nile. Heuglin, in his map, destroys all connexion between the 

 Blue Nile and the Tana Sea, but unfortunately says nothing in 

 explanation of his doing so. There are, however, one or two 

 facts which, although not absolutely inconsistent with the Tana Sea 

 being united to the Nile, are in perfect harmony Avith its not being 

 so. Bruce mentions one — namely, that there are no crocodiles in 

 the Tana Sea. Heuglin states that most of the species of fish 

 found in it (they belong chiefly to the Cyprinidae) are not found in 

 the Nile, a fact, however, of less value than it looks like, for many 

 of the fishes of the Upper Nile themselves are different from those 

 which inhabit the lower part of its course. 



There still remains another interesting point for inquiry relating 

 to the Manatee in the Tana Sea, and which we may hope that our 

 expedition will be able to clear up — and that is, whether it is a 

 Manatee or a Dugong — the one being the representative of the 

 sea cow in the Atlantic, the other in the Indian Ocean. The 

 Dugong has been found in the Red Sea, so at first sight we may 

 anticipate that the Manatee in the Tana Sea will most probably be 

 the Dugong; but seeing that through the Sahara the Atlantic 

 so recently flowed across Africa, we confess that we should by no 

 means be surprised should the animal be the same as, or at least 

 nearest to, the Atlantic Manatus Senegalensis. The steps by 

 which such changes in level, as we have been speculating on have 

 been effected, will hereafter be matter for the study of geologists. 

 At present all that we know about the geological structure of the 

 Highlands of Abyssinia is, that it is almost entirely composed of 

 granite, basalt, and trachyte. Great quantities of pumice-stone are 

 scattered over many parts of it, and the volcanic character of the 



TRAVFX M 



