rence; and Nepa has only one, of which but few other instances are afforded by the class.
The general forms and relative position of the parts described, will be well understood from an inspection of Plate XVIII. which represents the details of a characteristic example of each of the two great divisions of this order.
Fig. 6 is a highly magnified view of an insect belonging to the heteropterous section, Pentatoma rafipes, a common British species. The wings on one side are expanded, the others in situ. For greater perspicuity, the various segments, where covered by superincumbent organs, are represented by dots. H, the head; a, a, the eyes; b, the ocelli; c, one of the antennæ; T 1, upperside of the prothorax; l′ one of the prothoracic legs; T 2, upperside of the mesothorax; S c, scutellum greatly developed and extending over the metathorax and part of the abdomen; h one of the hemelytra; hc, the leathery basal portion of the hemelytra; hm, the membranous or apical portion; l″ one of the mesothoracic legs; T 3, upper side of the metathorax, greatly reduced in size, supporting the wings (one of which is extended, W 2), and the metathoracic or third pair of legs l′′′—A, abdomen.— Fig. 7. The head and prothorax of the same insect seen from beneath; a, the eye; c, base of antennæ; lr, labrum or upper-lip, long, and transversely striated; lb, the four-jointed lower-lip transformed into an elongated canal for the reception of four slender setæ, gg, hh, which represent the mandibles and maxillæ; s, raised portion of the underside of the head, forming a gutter, in which the base of the labrum rests; T 1, underside of the prothorax; l′ base of one of the prothoracic legs; Z, the cavity of the prothorax, into which the anterior narrowed part of the mesothorax (marked in fig. 6 by the letter z) is received.—Fig. 8. Side view of the head, the respective parts lettered as in fig. 7.—Fig. 9. One of the anterior tarsi of Pentatoma rufipes, shewing the emargination at the base of the tibia, and the pulvilli attached to the base of the claws.
