Page:Handbook for Boys.djvu/118

Rh "Mollusks of the Chicago Area" and "The Lymumiæidæe 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, punes, 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 extreme southern end of Florida. The turtles are easily recognized by the bony covering which encases their body, and into which most species can withdraw their heads and legs for protection. This bony box is usually covered with horny plates, but in a large group, the so-called salt-shell turtles, the outer covering is a soft skin, thus forming a