The rays and skates are also carnivorous, but are with few exceptions sluggish, lying at the bottom of shallow shore-waters. They feed on crabs, molluscs, and bottom-fishes. The small common skates, "tobacco-boxes" (_Raja erinacea_) (fig. 114), about twenty inches long, and the larger "barn-door skates" (_R. lævis_), are numerous along the Atlantic coast from Virginia northward. Especially interesting members of this group, because of the peculiar character of the injuries produced by them, are the sting-rays and torpedoes or electric-rays. The sting-rays (_Dasyatis_) have spines near the base of the tail which cause very painful wounds. The torpedoes (_Narcine_) have two large electrical organs, one on each side of the body just behind the head, with which they can give a strong electric shock. "The discharge from a large individual is sufficient to temporarily disable a man, and were these animals at all numerous they would prove dangerous to bathers." Very different from the typical rays in external appearance are the saw-fishes (_Pristis pectinatis_) which belong to this group. The body is elongate and shark-like, and has a long saw-like snout. This saw, which in large individuals may reach a length of six feet and a breadth of twelve inches, makes its owner formidable among the small sardines and herring-like fishes on which it feeds. The saw-fishes live in tropical rivers, descending to the sea. [Illustration: FIG. 114.--The common skate, _Raja erinacea_. (From Kingsley.)] =The bony fishes (Teleostomi).=--The bony or true fishes are distinguished from the lampreys and sharks and rays by having in general the skeleton bony, not cartilaginous, the skull provided with membrane bones, and the eggs small and many. In this group are included all the fishes of our fresh-water lakes, ponds, and streams as well as most of the marine forms. Fish life, being spent under water, is not familiar to most of us, and beginning students are rarely helped enough in getting acquainted with the different kinds and the interesting habits of fishes. But they offer a field of study which is really of unusual interest and profit. We can refer in the following paragraphs to but few of the numerous common and readily found kinds, and to these but briefly. Closely related to the sunfish, studied as example of the bony fishes, are the various kinds of bass, as the "crappie" (_Pomoxis annularis_), the calico bass (_P. separoides_), the rock-bass (_Ambloplites rupestris_) and the large-mouthed and small-mouthed black bass (_Micropterus salmoides_ and _M. dolomieu_ respectively). All the members of this sunfish and bass family are carnivorous fishes especially characteristic of the Mississippi valley.