ENTOGNATHY IN APTERYGOTES — TUXEN 



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probably the last-named muscles attach to the so-called dorsal arms of 

 the fulcrum. Furthermore, a very thin muscle from the hind wall 

 of the head is attached through a long ligament (mLc) to the median 

 outgrowth of a sclerotized plate from lacinia i, corresponding to the 

 muscle a in Campodea, except that it is placed ventrally to the other 



0.01 mm 



Fig. 21. — Acerentomon dodcroi Silv. Fore part of head with the two halves 

 of labium spread out and the maxillae as if spread out. (After a slide in the 

 Berlese collection in Firenze, No. 3.8.) Labium closely dotted, maxillae openly 

 dotted. 



muscles in Acerentomon. And finally a palpal muscle, c, is found run- 

 ning from the proximal part of the stipes to the basal part of the first 

 palpal joint (what Berlese calls the second joint). Berlese (Tav. V, 

 fig. 36) has drawn this muscle to the very tip of the palpus, but I have 

 not been able to follow it so far, nor is it very probable, because, as 

 figure 20 shows, the outermost segments in retraction are unchanged. 



