280 LAWS OF ANIMAL DISPERSION. 
‘animals is in the arctic and antarctic seas, different 
species occurring at these two extremes; they 
gradually diminish in number as we enter the tem- 
perate regions, and are at their minimum in the 
equatorial seas. The Turtles and Tortoises are 
chiefly inhabitants of the warm latitudes, yet they 
extend sparingly northwards, and even in England 
a few stray individuals have been captured—the 
Hawk’s bill Turtle in the Severn, in Orkney, and 
in Zetland, and the Leathern Tortoise in Cornwall. 
Peron says, “ the seat of the Phasianelle is at Maria 
Island ; all traces of them are lost at King George’s 
Sound, after passing through insensible degrada- 
tions.” ‘The corals and other zoophites so plentiful 
and luxuriant in tropical seas, are replaced in tem- 
perate climes by (for the most part) a new series 
of less sizeand less luxuriantaspect; yet the tropical 
genera and species still follow us in sparing quan- 
tities. In England, the madrepores are reduced 
to two or three species of rare occurrence and di- 
minutive size; the Gorgoniz are also comparatively 
small; but the Gorgonia flabellum of the tropics 
has been two or three times found on the Cornish 
and Leith shores. Instances of this kind might 
readily be multiplied. 
It appears from the foregoing remarks that how- 
ever desirable it might be in all inquiries like the 
present, to determine general or primary laws, and 
that however obvious it may be that such deter- 
minations should be the principal aim of naturalists, 
yet the subject we are enquiring into will scarcely 
allow us to proceed farther than the discovery of 
secondary influences. And since these are liable 
to have an undue importance ascribed to them and 
to be viewed as primary laws, it would be right as 
far as possible to ascertain their absolute weight, 
and to see how far they modify those more general 
influences. 
