_Apterous, blind Insects with exserted head, having a constricted neck, mouth placed quite inferiorly; the thoracic sterna large, imbricate. Hind body elongate, the segments imbricate, the dorsal plates being large and overlapping the ventral; the number of visible segments being different according to sex: a pair of long unsegmented cerci at the extremity. Coxae small, widely separated. Development intra-uterine._ [Illustration: Fig. 114.—_Hemimerus hanseni_, female. Africa. (After Hansen.)] [Illustration: FIG. 115.—Under side of head and front of prothorax of _Hemimerus_. _a_, base of antenna; _b_, articulation of antenna; _c_, labrum; _d_, mandible; _e_, condyle of mandible; _f_, articular membrane of mandible; _g_, stipes of maxilla; _h_, exterior lobe; _i_, palpus of maxilla; _k_, submentum; _l_, mentum; _m_, terminal lobe of labium; _n_, labial palp; _o_, plate between submentum and sternum; _p_, prosternum; _q_, cervical sclerites. (After Hansen.)] In describing the labium of Mandibulata, p. 97, we alluded to the genus _Hemimerus_ as reputed to possess a most peculiar mouth. When our remarks were made little was known about this Insect; but a very valuable paper[145] by Dr. H. J. Hansen on it has since appeared, correcting some errors and supplying us with information on numerous points. M. de Saussure described the Insect as possessing two lower lips, each bearing articulated palpi, and he therefore proposed to treat _Hemimerus_ as the representative of a distinct Order of Insects, to be called Diploglossata. It now appears that the talented Swiss entomologist was in this case deceived by a bad preparation, and that the mouth shows but little departure from the ordinary mandibulate type. There is a large inflexed labrum; {218}the mandibles are concealed by the maxillae, but are large, compressed, and on their inner edge toothed. The maxillae are well developed, are surmounted by two lobes and bear five-jointed palpi. The ligula appears to be broad and short, and formed of two parts longitudinally divided; the short palpi consist of three segments. The mentum is very large. The lingua is present in the form of a free pubescent lobe with a smaller lobe on each side. The structure of the pleura is not fully understood; that of the abdomen seems to be very like the earwigs, with a similar difference in the sexes. The cerci are something like those of Gryllidae, being long, flexible, and unsegmented. The legs have rather small coxae, and three-jointed tarsi, two of which are densely studded with fine hairs beneath, as in Coleoptera. It is difficult to detect the stigmata, but Dr. Hansen believes there are ten pairs. [Illustration: FIG. 116.—Foetus of _Hemimerus_. (After Hansen.) _a_, Antenna; _b_, organ from the neck; _c_, cerci; _d_, membrane (? cast skins).] [Illustration: FIG. 117.—_Hemimerus talpoides_. Africa. (After de Saussure.) A, Upper; B, under surface.]