THE PHYLOGENETIC SIGNIFICANCE OF 



ENTOGNATHY IN ENTOGNATHOUS 



APTERYGOTES 



By S. L. TUXEN 

 Copenhagen, Denmark 



In recent years more and more voices are raised in support of a 

 separation of entognathous apterygotes from the ectognathous ones, 

 of removing the entognathous ones from the class Insecta, and even 

 of removing them very far from each other. Thus, Handschin in 1952 

 urged that the Collembola should be made a class of its own — Proto- 

 morpha. Remington in 1954 summarized what was to be said on this 

 matter in a clear and scholarly paper and gave his own opinion to 

 the effect that "Myriapoda" and Insecta might be grouped as a sub- 

 phylum Insecta subdivided in sections, superclasses, and classes as 

 follows : 



Subphylum Insecta 

 Section Myocerata 

 Superclass Dignatha 

 Class Pauropoda 

 Class Diplopoda 

 Superclass Trignatha 

 Class Chilopoda 

 Class Labiata 



Order Collembola 

 Order Protura 

 Order Symphyla 

 Order Entotrophi (= Diplura) 

 Section Amyocerata 

 Class Thysanura 

 Class Pterygota 

 Subclass Paleoptera 

 Subclass Neoptera 



Paclt, on the other hand, in a discussion with Hennig (1954 and 

 1956a) and in his compilatory work of 1956(b) concluded that wing- 

 lessness among what he (as well as Remington) calls primitively 

 wingless insects (also adopted by Sharov in his papers on Thysanura 

 and Monura) is a monophyletic character, all apterygotes being one 

 group, at the base of Insecta. 



Obviously, it is a purely verbal problem whether or not to call the 



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