196 
ZOOLOGICAL GEOGRAPHY. 
[PART III* 
snakes. Of the lizards, Lacerta stirpium (the sand lizard) has 
the most northerly range, extending into Poland and Northern 
Russia; and Anguis fragilis (the blind or slow- worm) has almost 
an equal range. 
Amphibia, being more adapted to a northern climate, have 
acquired a more special development, and thus several forms 
are peculiar to the North European sub-region. Most remarkable 
is Proteus , a singular eel-like aquatic creature with small legs, 
found only in the subterranean lakes in Carniola and Carinthia ; 
Alytes , a curious toad, the male of which carries about the eggs 
till they are hatched, found only in Central Europe from 
France to the east of Hungary ; and Pelodytes, a frog found only 
in France. Frogs and toads are very abundant all over Europe, the 
common frog (. Rana temporaria) extending to the extreme north. 
The newts ( Triton ) are also very abundant and widely spread, 
though not ranging so far north as the frogs. The genera Bom- 
binator (a toad-like frog), and Hyla (the tree frog) are also com- 
mon in Central Europe. 
Freshwater Fish. — Two genera of the perch family (Percidse) are 
peculiar to this sub-region, — Percarina , a fish found only in the 
river Dniester, and Aspro, confined to the rivers of Central 
Europe. Of the very characteristic forms are, Gasterosteus 
(stickle-back), which alone forms a peculiar family — Gasteros- 
teidse ; Perea, Acerina and Lucioperca , genera of the perch family ; 
Silurus , a large fish found in the rivers of Cenrtal Europe, of 
the family Siluridae ; Esox (the pike), of the family Esocidae ; 
Cyprinus (carp), Gobio (gudgeon), Leuciscus (roach, chub, dace, 
&c.), Tinea (tench), Abramus (bream), Alburnus (bleak), Cobitis 
(loach), all genera of the family Cyprinidse, 
Insects — Lepidoptera. — No genera of butterflies are actually 
confined to this sub-region, but many are characteristic of it. 
Pamassius, Aporia , leitcophasia , Colias , Melitcea , Argynnis , 
Vanessa, Limenitis, and Chionobas , are all very abundant and 
widespread, and give a feature to the entomology of most of the 
countries included in it. 
Coleoptera . — This sub-region is very rich in Carabidfe; the 
genera Elaphrus, Nebria, Cardbus, Cychrus, Pterostichus, Amara, 
