186 ZOOLOGICAL GEOGRAPHY. [part hi. 



that may fairly be considered as exclusively or characteristically 

 Palaearctic. 



Reptiles and Amphibia. — The Palaearctic region possesses, in 

 proportion to its limited reptilian fauna, a full proportion of 

 peculiar types. We have for instance two genera of snakes, 

 Rhinechic and Halys ; seven of lizards, Trigonophis, Psammo- 

 dromus, Hyalosaurus, Scincus, Ophiomorus, Megalochilus, and 

 Phrynocephalus ; eight of tailed batrachians, Proteus, Salaman- 

 dra, Seiranota, Chioglossa, Hynobius, Onychodactylus, Geotriton, 

 and Sieboldia ; and eight of tail- less batrachians, Bombinator, 

 Pelobates, Didocus, Alytes, Pelodytes, Discoglossus, Laprissa, and 

 Latonia. The distribution of these and other Palaearctic genera 

 will be found in our second vol. chap. xix. 



Freshwater Fish. — About twenty genera of freshwater fishes 

 are wholly confined to this region, and constitute a feature which 

 ought not to be overlooked in estimating its claim to the rank 

 of a separate primary division of the earth. They belong to the 

 following families : — Percidae (three genera), Acerina, Percarina, 

 Aspro ; Comephoridae (one genus), Comcphorus, found only in 

 Lake Baikal ; Salmonidae (three genera), Brachymystax, Lucio- 

 trutta, and Plecoglossus ; Cyprinodontidae (one genus), Tellia, 

 found only in Alpine pools on the Atlas Mountains ; Cyprinidae 

 (thirteen genera), Cyprinus, Carassus, Paraphoximis, Tinea, 

 Achilognathus, Rhodeus, Chondrostoma, Pseudoperilampus, Oche- 

 tebius, Aspius, Alburnus, Misgurnus, and Nemachilus. 



Summary of Palaearctic Vertebrata. — Summarising these de- 

 tails, we find that the Palaearctic region possesses thirty-five 

 peculiar genera of mammalia, fifty-seven of birds, nine of 

 reptiles, sixteen of amphibia, and twenty-one of freshwater 

 fishes; or a total of 138 peculiar generic types of vertebrata. 

 Of these, 87 are mammalia and land-birds out of a total 

 of 274 genera of these groups ; or rather less than one-third 

 peculiar, a number which will serve usefully to compare with 

 the results obtained in other regions. 



In our chapter on Zoological Eegions we have already pointed 

 out the main features which distinguish the Palsearctic from the 

 Oriental and Ethiopian regions. The details now given will 



