d
on the seashore and the water near the shore, and a collection of them
will not only contain many curious, pretty, and interesting things,
but will have the advantage of requiring no preservative to keep them
in good condition after the animal has been taken out.

[Illustration: Fig. 4 Orb-Shell (Planorbis trivolvis)]

[Illustration: Fig. 5 Black Mussel (Mytilus)]

[Illustration: Fig. 6 Bubble snail (Physa heterostropha)]

The squids, cuttle-fishes, octopus, and their allies are also
mollusks, but not so accessible to the ordinary collector, and can
only be kept in spirits.

Books which may help the collector to identify the shells he may find
are:

For the land and fresh-water shells: {97}

"Mollusks of the Chicago Area" and "The Lymnaeidae of North America."
By F. C. Baker. Published by the Chicago Academy of Sciences.

For the American Marine Shells: Bulletin No. 37. Published by the
United States National Museum, at Washington.

For shells in general: "The Shell Book." Published by Doubleday, Page
& Co., Garden City, N.Y.

On the Pacific Coast the "West Coast Shells," by Prof. Josiah Keep of
Mills College, will be found very useful.

REPTILES

_By Dr. Leonhard Stejneger, Curator National Museum_

By reptiles we understand properly a certain class of vertebrate or
backboned animals, which, on the whole, may be described as possessing
scales or horny shields since most of them may be distinguished by
this outer covering, as the mammals by their hair and the birds by
their feathers. Such animals as thousand-legs, scorpions, tarantulas,
etc., though often erroneously referred to as reptiles, do not concern
us in this connection. Among the living reptiles we distinguish four
separate groups, the crocodiles, the turtles, the lizards, and the
snakes.

The crocodiles resemble lizards in shape, but are very much larger and
live only in the tropics and the adjacent regions of the temperate
zone. To this order belongs our North American alligator, which
inhabits the states bordering the Gulf of Mexico and the coast country
along the Atlantic Ocean as far north as North Carolina. They are
hunted for their skin, which furnishes an excellent leather for
traveling bags, purses, etc., and because of the incessant pursuit are
now becoming quite rare in many localities where formerly they were
numerous. The American crocodile, very much like the one occurring in
the river Nile, is also found at the extr