104 BULLETIX: MUSEUM OF COMPARATIVE ZOOLOGY. 



21. He also gives a figure (Taf. V., Figur 64) supporting his state- 

 ment (p. 22) concerning the appearance of the mandibular segments : 

 " Ausserdem [collection of entoderm cells, etc.] bemerkt man zwei Paar 

 dunkler Stella, welche an .den Ecken eines gedachten Quadrats sicli 

 befinden. Das dem Dorsalorgane genaherte Paar dieser Blastodermver- 

 dickungen (kl.) sind die getrennten Aulagen der Kopflappen, das zweite 

 Paar (jnds.) stellt die getrennten Anlagen des Mandibularsegmentes vor." 

 The eggs of Aiiurida at my disposal were either too old or too young to 

 show the condition here described by Uzel, although I did find a stage 

 in which three pairs of fundaments were present, the third pair being 

 the first maxillae. The mandibles probably follow the procephalic lobes 

 in appearance, as I have found all the stages necessary to indicate that 

 the remaining paired appendages, except those of the superlingua3, as I 

 shall term them, appear successively from in front backward. 



Campodea is structurally nearest to the Collembola, and, thanks to 

 Uzel ('98, Taf. III., Figuren 35, 36; Taf. VI., Figuren 77-85), some- 

 thing is known concerning the development of its mouth-parts. The 

 mandibular fundaments of Campodea are simple papillae, as in Collem- 

 bola ; this simplicity distinguishes the Apterygota from the most gener- 

 alized Pterygota, the Orthoptera, in which the fundaments are sometimes 

 lobed. 



The finished mandible of Campodea is strikingly like that of the 

 Collembola, and is, moreover, of great morphological interest, because 

 the structural correspondence of the mandible with the maxilla of hexa- 

 pods — obscure in almost all other insects — is here a matter of direct 

 observation, not merely one of inference. The mandible of Campodea 

 (Meinert, '65, Taf. XIV., Figuren 15, 16 ; Nassonow, '87, p. 33, Figur 

 27) consists of a hollow fulcrum (stipes) and a head, which is separated 

 from the fulcrum by a transverse suture. The head is composed of two 

 parts, — a large, toothed, immovable, outer lobe or galea, and a smaller, 

 fringed, movable, inner lobe, representing the lacinia. 



Accepting the homologies with the first maxilhu imj^ied in these 

 terms, the palpus remains to be accounted for. A mandibular palpus has 

 never been found among adult insects, — the evidence given for one 

 by Ilollis ('72) being quite vague and inadequate. Although the de- 

 tailed development of the mouth-parts of Campodea has never been 

 followed, it is in this most generalized insect that one may most hope- 

 fully look for a trace of a mandibular pal[)us, and we may safely predict 

 that, if found, it will be a lateral, distal lobe of the stipal region, just as 

 it is in the maxilhc of all insects. 



