Note 12 — PART I.—MORPHOLOGY AND PHYSIOLOGY (continued 2)

We may add, while correcting the proofs of this book, that the important summary, by Uzel, of his work on the embryology of Campodea appears in the Zoologischer Anzeiger for July 5, 1897. He observes that the premandibular segment in the embryo is very distinct, and that the two projections arising from it persist in the adult. “Campodea is now the first example where these appendages are present in the sexually mature insect and function as constituents of the completed mouth parts. I propose for these hitherto overlooked structures the name of intercalary lobes.” They each form a slightly developed chitinous lobe covering a gap between the base of the labium and the fused external lobe and palpus of the first maxillæ (which are inclined near the labium) in place of the mandibles which have sunken inward. Uzel also homologizes these appendages with two similar projections (Höcker) observed in the embryo of Geophilus by Zograf to be situated in front of the mandibles. Heymons has also detected this segment in the embryo of Lepisma.