272 Journal New York Entomological Society. [Voi. xxiv. 



hood " and are characterized as follows. Styli absent, and segmented 

 cerci wanting, although unsegmented appendages termed " cerci " 

 may be present in such forms as Tomoceriis, etc. Mouthparts of the 

 concealed type in all of the members of the group. Uropods, or 

 true abdominal legs usually present, either in the form of the vestigeal 

 abdominal legs of the Protura, or the modified abdominal legs which 

 form the ventral tube (columella), tenaculum, and springing appa- 

 ratus (or furcula) of the other members of the section. Antennae 

 may be absent as in the Protura, although Schepotieff, 1909, has 

 figured and described them for " Protapteron " — but this is stated to 

 be a "lapsus calami'' by Prell, and others. In other forms the 

 antennae are usually short and composed of only six segments — al- 

 though an "annulation" of the terminal antennal segments occurs 

 in certain members of the group. The so-called " pseudoculus " of 

 the Protura, and the postantennal organ of the other forms, are 

 doubtless the homologues of Tomosvary's organ in the " Myrio- 

 poda." In addition to this, the general character of the alimentary 

 tract, the reproductive organs, the segmentation of the Q.g%, and the 

 embryological development, etc., of the members of this group, 

 clearly suggest " Myriopodan " affinities. Some of the families con- 

 tained in this section (which is the only non-styli-bearing one) are 

 the Eosentomidse, Acerentomidae, Neelidae, Sminthuridse, Achorutidae, 

 Entomobryidae, etc. 



The second section (which is a division of the styli-bearing 

 Apterygota) comprises those insects which group themselves about 

 the Rhabdura (Campodea, etc.) forming the section Rhahduradelphia, 

 or " Rhabduran-brotherhood." In some respects, such forms as 

 Anajapyx are more primitive than the true Rhabdura (such as 

 Campod.-'a), but the term Rhabdura, being better known, has, on this 

 account, been chosen to illustrate the group as a whole. In the insects 

 belonging to this section, styli are usually borne on the first seven 

 abdominal sterna, but may be lacking on the first (Campodea). 

 Cerci, in the form of paired segmented caudal filaments, or modified 

 to form the forceps-like terminal abdominal appendages of Japyx, 

 etc., occur in all of the members of the group thus far observed; but 

 a median unpaired terminal caudal filament (characteristic of the 

 next group to be considered) is always wanting. All of the mem- 

 bers of this section have mouthparts partially or wholly of the con- 



