13^ M. P. Gervais on the Freshwater Fishes of Algeria. 



Guichenot *). This latter exists also in various localities of the 

 Mediterranean region ; every one knows the geographical distri- 

 bution of the preceding species. 



Having more recently received from M. Paul Mares, a natu- 

 ralist whose labours with relation to Algeria are appreciated by 

 the Academy, some fishes from that country, with the request 

 that I would examine them, I have been led to revise the results 

 of my former investigation, and can make some additions to it 

 which are not without interest. 



The fishes collected by M. P. Mares enable me to add two 

 genera to the above list. I shall avail myself of the opportunity 

 which they present to make some new observations with regard 

 to the Cyprinodontes, and to establish more accurately than I 

 could formerly the synonymy of Coptodus. 



The first of the two genera, new as Algerian, which I shall 

 indicate from the fishes sent to me by M. P. Mares is the genus 

 Gobius, the species of which are chiefly marine, but which, 

 nevertheless, furnishes a few to the fresh waters of the south of 

 Europe. Bonelli and Cuvier have mentioned such as occurring 

 in Piedmont and about Bologna ; there are also some in eastern 

 Europe, especially in Austria and the south of Russia. Pallas 

 indicated one ; and others have been described by MM. Heckel 

 and Nordmann. Gobius lacteus, Nordmann, is from the 

 Dniester. 



The Algerian Gobii were taken in the rivulets of the environs 

 of Guelma ; I have been unable to compare them with those 

 previously described, and consequently cannot affirm that they 

 clifier specifically from them. 



A second genus which had not been observed in Algeria is 

 Gasterosteus, well known by its European species. It occurs 

 also in North America, but has not previously been indicated in 

 any part of Africa. Specimens have been taken near Algiers, 

 in the rivulets in the vicinity of the Maison-Carree. They 

 belong to the group of Sticklebacks with three dorsal spines ; 

 and their principal characters approximate them to the species 

 or variety common in the environs of Paris, of which Cuvier has 

 made his Gasterosteus leiurus ; nevertheless some secondary dif- 

 ferences allow of their separation, and they seem to constitute a 

 distinct species. 



M. P. Mares has also sent me some Cyprinodons. They 

 came, like the Gobies, from the torrents of the environs of 

 Guelma, and do not appear to be specifically distinct from the 

 specimens previously received by M. Guichenot from Biskra. 

 They are likewise very similar to those which Captain Zickel saw 

 issuing with the water from the artesian well bored under his 

 * Revue et Magasin de Zoologie, 1859, p. 377. 



