APPENDIX C. 
205 
merely the offspring of that of the Upper Nile^ and therefore the 
propriety of making a distinction between them may be ques- 
tioned. When we examine more closely the lower Fauna^, we find 
that it consists 
1. Of several species of Grey Mullets (Mugil), one Shad (Alosa), 
and two species of Eel (Anguilla), which are simply immigrants, 
or periodical visitors from the Mediterranean, and never ascend 
beyond the cataracts. 
2. Of about thirty- seven species, which are also found in the 
Upper Nile, some of them at least are evidently carried down by 
the annual floods, and do not propagate their species in more 
northern latitudes ; but our information on this point is at present 
extremely meagre. 
3. About seventeen species of Siluroids, Cyprinoids, and Char- 
acinoids, have been hitherto found below the cataracts only ; but 
whether any of them are peculiar to the Lower Nile is a question 
which cannot be decided at present. 
The Fauna of the Upper Nile is at once distinguished by the 
absence of the Mediterranean forms mentioned above, and by the 
presence of fishes typical of tropical Africa, which never, or but 
very rarely, lose themselves into the lower part, and certainly do 
not propagate there. Such are Ctenopoma, OpJdocepJialus, Clarotes, 
Rhinoglanis , Haplochilus, Lepidosiren, and others. The number of 
species amounts to fifty-six, and of these not less than twenty-five 
are absolutely identical with West African species; so that the 
affinity between the West African rivers and the Upper Nile is 
not much less than that between the Upper and Lower, the latter 
having thirty-six species out of fifty-three in common with the 
