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210 be correct, which they are admitted to be in general, the mandibular teeth of the Orthoptera offer this peculiarity, that they have a coriaceous and transverse plate, (lame) at their base, which seems to separate them from the body of the mandible; whereas in other cases, the teeth are well known to be only projecting pieces of the substance of these organs. The same observer, adopting an idea first started by Knoch, regards these dentations as bearing so close a relation to the mode of nourishment, that by observing their structure, distinct intimation may be obtained of the kind of food used, and consequently in some degree of the habits of the respective species. He divides them according to their analogy to the dental system of mammiferous animals, into incisive, canine, and molar. The former are large, somewhat resembling a curved wedge, their external surface convex, and the opposite one concave; a form which renders them eminently fitted for cutting: the teeth at the extremity of the mandibles of Locusta exemplify this modification. The canine teeth are conic, often very sharp, and lengthened, and are of course characteristic of such genera as Empusa and Mantis, which are purely carnivorous. The molars are large, short, and fitted for bruising alimentary substances. Never more than one exists in each mandible situated at the base opposite to each other. The species provided with the first and last mentioned description of teeth are herbivorous; and when they exist simultaneously, which happens occasionally in such species as are