BRIEF NOTES ON FISHES. 353 



their presence. By the aid of aquaria we have been able 

 to remedy this difficulty to some extent ; but still, if the 

 habits of even our commonest fishes are to be thoroughly 

 known, w T e must patiently pass hours by the water-side, 

 and exercise our ingenuity in every way to determine 

 what is going on in the depths below. One simple way 

 of doing this, practicable at least in quiet ponds, is to 

 insert a silvered tube, with a flaring or trumpet mouth 

 protected by a glass disk, into the bottom of a boat or 

 raft, and then lying down, to cover yourself with a blan- 

 ket in order to exclude the light, and so quietly float 

 along, looking through the submerged tube into the 

 depths below. By this means you can see objects at 

 great depths, especially if the sun be shining. 



I was led to try this plan, because I had read, in Hen- 

 ry's "Travels in Canada," that in practically the same 

 manner the Indians of that country determined the 

 whereabouts of the large trout in winter, and speared 

 them through holes cut in the ice. This author says : 

 " In order to spear trout under the ice, holes being first 

 cut of two yards in circumference, cabins of about two 

 feet in height are built over them of small branches of 

 trees, and these are further covered with skins, so as 

 wholly to exclude the light. The design and result of 

 this contrivance is to render it practicable to discern ob- 

 jects in the water at a very considerable depth. ... So 

 completely do the rays of light pervade the element, that 

 in three-fathom water I have often seen the shadows of 

 the fish on the bottom following them as they moved, 

 and this when the ice itself was two feet in thickness." 



In the way that I have mentioned, years ago, I famil- 

 iarized myself with the every-day life of all our commoner 

 fishes ; saw what food they ate and how they procured it ; 

 learned what were their enemies and how thev avoided 



