The Embryology of Dacus Tryoni (diptera). 3. Origins of Imaginal Rudiments Other than the Principal Discs.

I N addition to the principal imaginal discs (cephalic, labial, wing, haltere, leg and genital), the larva in Cyclorrhapha carries as discrete components the rudiments of the imaginal segmental abdominal hypodermis, salivary glands, fore-, midand hind-gut, lateral cerebral ganglia and segmental tracheal system (Snodgrass, 1924; Bodenstein, 1950; Shatoury, 19566; Anderson, 1964, etc.). The embryonic origins of these rudiments have never been firmly established. The present paper describes their origins in the embryo and larva of Dacus tryoni (Frogg.) (Trypetidae), taking a further step in the elucidation of the developmental relationship between the cyclorrhaphan larva and adult.