II. 



Distribution of the Vertebrata. Fishes. Amphibians. Keptiles, Birds. 



Mammals. 



FISHES. 



THE geographical distribution of fishes is at the present day, 

 and probably has been for a considerable number of past geologi- 

 cal periods, world-wide. Although vastly more abundant, if not 

 individually at least specifically, in the regions of elevated tem- 

 perature than in those of the opposite extreme, both as regards 

 the marine and fresh- water forms, they are still far from wanting 

 in waters of icy coldness, whether these be in high latitudes, the 

 oceanic abysses, or elevated mountain lakes or streams. The offi- 

 cers of the British Polar Expedition, under command of Sir George 

 Nares, obtained specimens of the charr (Salmo arcturus and. S. 

 Naresii) from beyond the eighty-second parallel of north latitude, 

 the highest point at which fresh-water fishes have been observed, 

 and from a still higher latitude, the eighty-third, some half-dozen 

 species of shore fishes, among them a bull-head and cod (Cottus 

 quadricornis, Gadus Fabricii, Icelus hamatus, Cyclopteris spinosus, 

 Liparis Fabricii, Gymnelis viridis). 108 And were it not for the in- 

 superable obstacles that were interposed in the way of fishing, there 

 can be no doubt that many additional forms would have been dis- 

 covered. The number of forms that descend into, or inhabit, the 

 abyssal waters whose temperature is about that of freezing is very 

 considerable; Gtinther 109 enumerates thirty-nine species whose 

 range extends to, or passes beyond, the fifteen hundred fathom, 

 line, thus penetrating deep into the zone of icy coldness. In the 

 European Alpine region fishes (salmonoids) inhabit the lakes or 

 streams situated at about the level of perpetual snow, and there is 

 very little doubt that the same is the case in nearly all regions of 



