The mascalonge is common in the St. Lawrence basin and the Great Lakes, more abundant in the lakes of northern Wisconsin, less common in the upper Mississippi River, Chautauqua Lake. New York, and Conneaut Lake, Pennsylvania, and rare in the upper Ohio River and tributaries. It has a long body, somewhat compressed, its depth being about one-fifth of its length; the head is large, about a fourth of the length of the body, and flattened, with the lower jaw projecting. It has a terrible array of teeth of assorted sizes. On the edge of each side of the lower jaw are several long, bayonet-shaped teeth, from one-half to an inch apart; in the front part of the tip of the projecting lower jaw are a few short but sharp teeth, recurved; in the front part of the upper jaw are three clusters of long, fanglike teeth, standing out amidst the smaller, cardlike teeth; on the edge of the forward half of the upper lip is a row of small, but very sharp, recurved teeth; back of these on the roof of the mouth (vomer and palatines), and extending back from the fangs in front to the throat, are three rows of cardlike teeth, recurved and very sharp. The coloration and markings vary so much that several varieties have been needlessly established, as the variations are found in every locality, and do not seem to depend on habitat or environment. The usual color is dark gray, greenish or brownish, always darker on the back, lighter on the sides, and belly white or whitish. The fins usually have dusky or slate-colored spots or blotches; the lower fins and caudal fin are often reddish. The markings of the body vary a great deal. In the young the upper half of the body is covered with small, round black spots, which usually disappear or change their shape as they grow old. In mature fish the spots are more diffuse, sometimes enlarging to an inch or more in diameter, or by coalescing form vertical broad bands, while in others there are no distinct dark markings. And while all of these various markings are found in fish from the same locality there is no apparent structural difference.