Note 50 — Chapter IV
Reading edition
Professor J. Wood-Mason points out that in Machilis (one of the Thysanura) the mandible shows signs of segmentation, while the apical portion is deeply divided into an inner and an outer half. Ripe embryos of Panesthia (Blatta) javanica are said to exhibit folds which indicate the consolidation of the mandible out of separate joints, while the cutting and crushing portions of the edge are divided by a “sutural mark,” which may correspond to the line of junction of the divisions of a biramous appendage (Trans. Ent. Soc., 1879, pt. 2, p. 145).