Many of the smaller species of fishes, upon leaving these winter resorts, ascend small, clear brooks in large numbers for the purpose of depositing their eggs; as, when hatched in such a place, the young will be comparatively free from the attacks of the larger carnivorous forms.  Among the lowest vertebrate often found in numbers in early spring in these meadow rills and brooks is the lamprey, Ammocoetes branchialis (L.), or “lamper eel,” as it is sometimes called.  It has a slender eel-like body, of a uniform leaden or blackish color, and with seven purse-shaped gill openings on each side.  The mouth is fitted for sucking rather than biting, and with it they attach themselves to the bodies of fishes and feed on their flesh, which they scrape off with their rasp-like teeth.  Later in the season they disappear from these smaller streams, probably returning in midsummer to deeper water.  Thoreau, who studied their habits closely, says of them:  “They are rarely seen on their way down stream, and it is thought by fishermen that they never return, but waste away and die, clinging to rocks and stumps of trees for an indefinite period; a tragic feature to the scenery of the river bottoms worthy to be remembered with Shakespeare’s description of the sea floor.”

[Illustration:  A LAMPREY.]

A few of the fishes, as the mud minnow and smaller catfishes, together with most frogs, turtles, and salamanders, on the approach of winter, burrow into the mud at the bottom of the streams and ponds, or beneath logs near their margins.  There they live without moving about and with all the vital processes in a partially dormant condition, thus needing little if any food.

The box tortoise or “dry land terrapin,” the common toad, and some salamanders burrow into the dry earth, usually going deep enough to escape frost; while snakes seek some crevice in the rocks or hole in the ground where they coil themselves together, oftentimes in vast numbers, and prepare for their winter’s sleep.  In an open winter this hibernation is often interrupted, the animal emerging from its retreat and seeking its usual summer haunts as though spring had come again.  Thus I have, on one occasion, seen a soft-shelled turtle moving gracefully over the bottom of a stream on a day in late December, and have in mid-January captured snakes and salamanders from beneath a pile of drift-wood, where they had taken temporary refuge.

[Illustration:  TURTLE.]

With frogs, especially, this hibernation is not a perfect one, and there is a doubt if in a mild winter some species hibernate at all.  For example, the little cricket frog or “peeper” has been seen many times in mid-winter alongside the banks of flowing streams, and during the open winter of 1888-89 numerous specimens of leopard and green frogs were seen on different occasions in December and January, while on February 18th they, together with the “peepers,” were in full chorus.