THE ANNALS 



MAGAZINE OF NATURAL HISTORY. 



[FOURTH SERIES.] 

 No. 48. DECEMBER 1871. 



XLVII. — Memoir on the Hydrograj^Mcal System and the 

 Freshwater Fish of Algeria. By Lieut. -Colonel R. L. 

 Playfair, H.M. Consul General, and M. Letourneux, 

 Conseiller a la Cour d'Appel, in Algeria*. 



I. Hydrographical System. 



In Europe an admirable system of circulation restores to 

 the ocean the waters which the sun has taken from it, and 

 which, having escaped from their aerial reservoirs in the 

 clouds, are poured out on the surface of the earth. In every 

 country a network of natural canals reunites into one central 

 stream, and carries to the sea, the surplus of the rains and 

 snows which have fertilized the soil, in the same manner that 

 the venous system carries back the blood to the heart to be 

 purified and to serve for the regeneration of the bodily organs. 



In Algeria, on the contrary, the system is far from being so 

 simple : a very small part of the country is subject to ordinary 

 hydrographic laws ; in the rest the waters either return to the 

 clouds without passing through the sea or circulate in vast 

 subterranean lakes. 



A glance at the map of Algeria will suffice to show that 

 the country consists of three regions, as distinct in their 

 hydrographical features as in their climate and vegetation : 

 these are the Tell, the High Plateaux, and the Sahara. 



The first, occupying the littoral zone, Avith a breadth of 

 from 50 to 70 miles, is for the most part mountainous, watered 

 by copious rains, tempered by sea breezes, and possessing in 

 a high degree the ordinary Mediterranean features. 



The flora and fauna of the eastern portion do not differ 

 essentially from those of Sicily and Sardinia, while in the 

 west they resemble rather those of Spain f. 



* Communicated by the Authors, having been read at the Meeting of 

 the British Association in August 1871. 



t The separation of Spain from Africa hardly goes boynnd the limit of 



Ann.iL-Mag.X.If/st. Ser. 4. Vol. v in. 29 



