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Rh omnivorous, they are usually of small dimensions. (Plate VI. fig. 4, mandibles of the house cricket with incisive teeth. Fig. 4xa [sic], one of the mandibles of Acrydium, with a large molar plate near the internal base, b.) The organs which next require to be noticed, are the maxillæ or under jaws. As they are employed for a similar purpose as the mandibles, they have a corresponding development; they are in fact often of large size, and in their general forms not unlike those of the carnivorous coleoptera. They are always glabrous in this order, or clothed with such short hairs as to be almost imperceptible. The maxillary palpi, (Plate VI. fig. b, c) are always five-jointed in this order, whereas the normal number among the Coleoptera appears to be four. The portion called the blade of the maxilla, is that which forms the apical extremity; it is usually incurved and bifid at the tip, (Plate VI. fig. 5, a.) It bears externally a distinct lobe, corresponding to what are frequently described as internal maxillary palpi. The name galea or helmet is now applied to this piece, (Plate VI. fig. 5, b.) It is frequently palpiform, consisting of two joints, and in some instances, (as in Acrydium) apparently of three; but in all cases it is dilated at the extremity somewhat in the form of a helmet, being vaulted, and covering the apex of the maxillæ to which it is usually closely applied. This is an important piece owing to the part it takes in nutrition, and the permanence of its forms in different species.

The labium or under lip is rather of a more