152 Cockerell — The Scales of the African Cypniud Fishes. 



to ujiland streams, as may Ik? suggested liy the great number and 

 variety of species in Al)jssinia. 



Another interesting feature is tlie paljcarctir fauna, ])ni>r in 

 species, in north Africa. This fauna docs not have tilings all its 

 own way. It seems natural enough that Kthidjiian types should 

 come down the Xile into Lower Egypt, hut it is curious that the 

 surprisingly rich (as to species) fauna in the Atlas ^fonntains 

 should be mixed, Pahearctic and Ethioi)ian. Thi< seems to jmint 

 to former (IMiocene) conditions in the Sahara region, very (lill'erent 

 from those ol)served to-day. 



