The labrum is more or less deeply bilobed, especially in caterpillars and in adult Staphylinidæ, and has been thought by some writers (Kowalevsky, Carrière, and also Chatin) to represent a pair of appendages, but Heymons (1895) refutes this view, stating as his reason that the labrum arises between the two halves of the nervous system (protocerebrum), while all the true appendages arise on each side of the nervous system. (See also Fig. 34.) [Illustration: FIG. 25.—Front view of the head of _C. spretus_: _E_, epicranium; _C_, clypeus; _L_, labrum; _O_, _o_, ocelli; _e_, eye; _a_, antenna; _md_, mandible; _mx_, portion of maxilla uncovered by the labrum; _p_, maxillary palpus; _p′_, labial palpus. ] In the fleas (Siphonaptera) both the clypeus and labrum are wanting. While it apparently forms an anterior specialized portion of the procephalic lobes, Viallanes regarded it as belonging to the third, or his tritocerebral, segment, since the labral nerves arise from the tritocerebral ganglia. But since in all the early as well as late stages of embryonic life it appears to be situated in front of the mouth, it would seem to belong to the first segment. In the embryo of Blatta it first appears as a thick crescentic fold being slightly divided anterior to the mouth, and in Doryphora it appears as a heart-shaped or deeply bilobed prominence situated in front of the mouth (Wheeler). =The epipharynx and labrum-epipharynx.=—The epipharynx is the under surface or pharyngeal lining of the clypeus and labrum, forming the membranous roof of the mouth. As it contains the organs of taste and has been generally overlooked by entomologists, we may dwell at some length on its structure in different orders. Réaumur was, so far as we have been able to ascertain, the first author to describe and figure the epipharynx, which he observed in the honey bee and bumble bee, and called _la langue_, remarking that it closes the opening into the œsophagus, and that it is applied against the palate. According to Kirby and Spence, De Geer described the epipharynx of the wasp; and Latreille referred to it, calling it the _sous labre_. The name _epipharynx_ was bestowed upon this organ by Savigny, who thus speaks of that of the bees: “Ce pharynx est, à la vérité, non seulement caché par la lèvre supérieure, mais encore exactement recouvert par un organe particulier que Réaumur a déjà décrit. C’est une sorte d’appendice membraneux qui est reçu entre les deux branches des mâchoires. Cette partie ayant pour base le bord supérieur du pharynx, peut prendre le nom d’_épipharynx_ ou d’_épiglosse_.” He also describes that of Diptera. What Walter has lately proved to be the epipharynx of Lepidoptera was regarded by Savigny and all subsequent writers as the labrum.