FISH OF BRITISH ISLANDS. 415 
the larger sand-eel (Ammodytes lancea) we have two very 
conspicuous species. 
As the surface of the British islands exhibits a transition as 
it were from a northern to a southern 
character, from the firs of Scotland to 
the free-growing myrtles of the Devon 
coast, so the inhabitants of our seas 
pass through a great variety of form, 
from a northern to a southern type. While the rorqual of the 
Frozen Ocean not seldom strands on our northern and eastern 
coasts; the flying-fish of the equi- 
noctial seas sometimes appears 
within view of our southern shores ; 
and it is this peculiar position of 
our insular empire, fronting the 
colder and the warmer seas, which 
enriches its waters with such a variety of marine life. “ Several 
characteristic boreal forms find their southern limit within the 
northern half of our waters, and there 
some of the most striking and abundant 
kinds are chiefly developed in numbers, 
such as the cat-fish or sea-wolf (Ana- 
Sand-Eel. 
Grey Mullet. 
rhicas lupus), the scythe (Merlangus a ATES y 
carbonarius), the ling (Lota molva), 
the cod (Gadus morrhua), the lump-sucker (Cyclopterus 
lumpus), and even the herring (Clupea harengus). On the 
other hand, along the southern shores of England we find 
fishes becoming frequent which are distinctly of a southern 
Salmon. 
type, such as the grey and red mullets (Mugil cephalus and 
Mullus barbatus), the sea-bream, and, far more plentifully, 
