18G ZOOLOGICAL GEOGRAPHY. [part hi. 



that may fairly be considered as exclusively or characteristically 

 Palsearciic. 



BeiMcs and Afuj^hihia. — The Palajarctic region possesses, in 

 proportion to its limited reptilian fauna, a full proportion of 

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

 Rhinecliis and Hahjs ; seven of lizards, Trigonophis, Psamirio- 

 dromus, Hyaloscmrus, Scincus, Ophiomorus, Megalochilus, and 

 Phrynoceplialiis ; eight of tailed batrachians, Proteus, Scdaman- 

 dra, Seiranota, CMoglossa, Hijiiohius, Onycliodadylas, Geotriton, 

 and Sieholdia ; and eight of tail- less batrachians, Bomhinator, 

 Pelohatcs, Didocas, Alyfes, Pelodyfcs, Piscoglossvs, Laprissa, and 

 Latonia. The distribution of these and other Paloearctic genera 

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



Frcslavatcr 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, Pcrcarina, 

 Aspro ; Comephoridee (one genus), ComcjjJwrus, found only in 

 Lake Baikal ; Salmonidse (three genera), BracJiymystax, Lucio- 

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

 found only in Alpine pools on the Atlas Mountains ; Cyprinida; 

 (thirteen genera), Cyprinus, Carassas, Paraphoxinus, Tinea, 

 Acliilognatlms, Bhodeus, Chondrostoma, Pseudoperilanqms, Oche- 

 tehius, Aspius, Alhurnus, Misgurnus, and Ncmacliilus. 



Summary of Palaiarctlc Vertclrata. — Summarising these de- 

 tails, Ave find tliat the Palrearctic region possesses thirty-five 

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

 reptiles, sixteen of amphiltia, 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 Regions we have already pointed 

 out the main features which distinguish the Paliearctic from the 

 Oriental and Ethiopian regions. The details now given will 



