68 GEOGRAPHICAL DISTRIBUTION. 



While the Holarctic region is relatively meagre in its reptilian 

 fauna, it is preeminently the home of the tailed amphibians, newts, 

 salamanders, &c., of which we have the blind proteus (Proteus 

 anguinus), in the cavern-waters of Carinthia, Carniola, and Istria ; 

 the giant salamander, known as Sieboldia (Cryptobranchus), in 

 Japan, and its allied American form, the menopoma, the eel-like 

 sirens, mud-puppies (Necturus), and almost limbless amphiumes of 

 the Eastern and Southern United States; the true salamander and 

 triton in Europe and Asia, and their American representatives, the 

 amblystomes, to which the singular form known as the axolotl be- 

 longs. The European tail-less amphibians (frogs and toads) number 

 some dozen or more species of the genera Bombinator, Pelobates, 

 Alytes, Hyla, Discoglossus, Rana, and Bufo, the most broadly dis- 

 tributed of which appears to be Rana temporaria and R. esculenta, 

 the former extending its range eastward to Japan and America, and 

 northward in Norway to beyond the seventieth parallel of latitude. 



The fish-fauna of the Holarctic tract is characterised by the spe- 

 cial development, among fresh-water forms, of the carps (Cypri- 

 nidse), salmon (SalmonidaB), pikes (Esocidae), perches (Percidse), 

 sculpins or bull-heads (Cottidae), sticklebacks (Gasterosteidae), stur- 

 geons (Accipenseridse), and lampreys (Petromyzon), which are dis- 

 tributed over both the eastern and western divisions of the region. 

 The Cyprinoids are especially abundant, constituting, in the number 

 of species, according to Gunther (Ency. Brit., XII., p. 675), nearly 

 two-thirds (two hundred and fifteen species) of the entire fish-fauna 

 of temperate Europe (including the Mediterranean transition region) 

 and Asia, and more than one-third (one hundred and thirty-five 

 species) of the equivalent fauna of North America. The cat-fishes 

 (Silurida?), so eminently characteristic of the more southerly equa- 

 torial zone, are largely deficient in the number of species. Silurus 

 occurs in some of the Eurasiatic waters as an immigrant from India ; 

 most of the North American forms belong to the genus Amiurus. 

 Among the more distinctive ichthyic features separating the faunas 

 of the eastern and western divisions of the Holarctic realm are the 

 possession, by the former, of the barbels (Barbus) and cobitoids, 

 and, by the latter, of the suckers (Catostomida3), sun-fishes (Cen- 

 trarchidaB, most abundant in the Mississippi Valley), and two genera 

 of ganoid fishes, Amia and Lepidosteus, both of which occur as 

 fossils in the Tertiary deposits of North America, and the latter 



