RIVER GARDENS; 
which they are placed, and that their natural colours 
are frequently the result of the colour of the soil 
forming the beds of their native streams. A simi¬ 
lar kind of susceptibility is also found in other 
fishes—a circumstance which is, in fact, a means of 
defence, as rendering them less conspicuous in the 
water. Dr. Stark tells us that he once observed a 
shoal of Flounders, on the flat sandy part of the 
coast of Holland, so exactly the colour of the sand 
over which they were swimming, as to be hardly 
distinguishable from it. 
But I must hasten to describe the most interest¬ 
ing instincts that honourably distinguish the little 
Stickleback. I of course allude to those connected 
with his habits of nidification. 
Nest-architecture is generally thought to be 
almost entirely confined to birds; the number of 
quadrupeds which attempt nest-building being very 
few, and those few not remarkable for any special 
skill. Indeed, even in these cases, such as the “nest ” 
of the Squirrel, the Field-mouse, the Babbit, and a 
few others, it is rather a “bed” for the young, than a 
receptacle for the deposition and production of eggs, 
which is alone the character of a true nest. 
The only true nests, therefore, except those of 
birds, are constructed by fish. This, consider- 
