27 
polar bear; too cold for the touraco and the hum- 
ming bird; too hot for the eider duck, perhaps for 
the fieldfare and brambling in summer ; too cold for 
numerous lizards, and most of the snakes, yet the 
lacerta aquatica is found torpid indeed, but embedded 
in ice in Lapland. The herrings which abound in 
the northern seas are unknown between the tropics. 
The tropical seas abound with genera unknown to 
the more temperate, and of course to colder lati- 
tudes. Many of the crustacea, both of land and 
water, never pass the tropics. The Mediterranean 
sea has many which never reach the British chan- 
nel. We are safe from the scorpion, and need not 
regret the absence of some singular varieties of crabs 
and crayfish. The cancer Norwegicus, of a pale 
red, mottled with yellow, is not found even so far 
south as our coasts. The land crab abounds in the 
Bahamas, but does not appear beyond the tropics. 
A species of humble bee, bombus arcticus, is not 
known to leave the arctic circle: the bombus lap- 
ponicus is found a little further south: the dytiscus 
marginalis, common in Greenland, is found through- 
out Europe. Elevation of land above the level of 
the sea must in this view be considered as equiva- 
lent to variation of climate; at least to the change 
from the climate of the mountain base to that of its 
summit’. Meridians of longitude also limit the dis- 
tribution of insects. Mr. Latreille enumerates in- 
sects which he calls meridional, onitis, mantis, ful- 
' Kirby, vol. iv. p. 485. 
