M. P. Gervais on the Freshwater Fishes of Algeria. ]33 



care at Ain-Tala, as cited by M. Desor in his note on the Alge- 

 rian Sahara *. Lastly, it is no less difficult to distinguish them 

 from fishes of the same genus which are found in Portugal, 

 Spain, Sardinia, and even in the neighbourhood of the Dead 

 Sea, as well as in other circum-Mediterranean localities. It 

 seems to me that it would be useful to make a careful compa- 

 rison of the Cyprinodons of these different localities before ad- 

 mitting that they constitute so many distinct species as ichthyo- 

 logists have supposed. Nevertheless I shall not include in this 

 synonymy, even generically, the Tellia, which certainly belongs 

 to the same family as the Cyprinodons, but differs from them by 

 the absence of the ventral fins. The Tellia has the mouth 

 clearly different from that of the Cyprinodons, having its aper- 

 ture more raised ; and it is an error to attribute its apodal cha- 

 racter to the wearing of its ventrals, as supposed by M. Desorf, 

 since not only the rays of these fins are wanting, but also the 

 pelvic bones which support them in other fishes. This is easily 

 ascertained by the examination of the specimens of Tellia depo- 

 sited by M. Guy on in the Paris Museum, as has been done by 

 M. Valenciennes J. 



The number of genera of Pish observed in Algeria is thus 

 raised to nine, namely : — 



Of the Acanthopterygii, the genera Coptodus or Tilapia, 

 Gobius, and Gasterosteus. 



Of the Malacopterygii abdominales, the genera Cyprinodorij 

 Tellia^ Barbus, Leuciscus, and Salar, 



Of the Malacopterygii apodes, the genus Anguilla. 



These nine genera only present as yet eleven species, even 

 including Barbus lonyiceps. It has been supposed that Pikes 

 exist in Algeria, and the lake Petzara has been indicated as 

 containing them ; but hitherto this assertion has not been con- 

 firmed. 



Of the nine genera ascertained, only one, Tilapia, to which 

 I have given the name of Coptodus, belongs to a family not 

 represented in the fresh waters of Europe. With regard to 

 this I have made some new observations which deserve to be 

 recorded. 



This fish has already been found in Algeria at several points 

 in the Sahara-region, at Biskra, Tuggurth, and Tmacin, and 

 in the lake of Farfar. I owe the specimen formerly describe(J 

 by me to M. Zill, a very distinguished naturalist, who sent it 

 to me during my journey to Constantine in 1848; he had 

 brought it from Tuggurth several years before. M.-Guyon also 



* Bull. Soc. Sci. Nat. de Neiichatel, 1864. 



t Loc. cit. 



X Comptes Rendus, Ivi. p. 713 (1858). 



