CLASSIFICATION 5 



by itself, Symphyla, presents a remarkable combination of diplopodan 

 and insectean characters. Scolopendrella (Fig. 6) and the thysanuran 

 Campodea have the same kind of head, with its long moniliform antennae, 

 and agree in the general structure of the mouth parts; the number of 



FIG. 6. Section of Scolopendrella immaculata. b, Brain; c, coxal gland; /, fore intestine; 

 //, hind intestine; m, mid-intestine; n, nerve chain; 0, opening of silk gland; od, oviduct; ov, 

 ovary; s, silk gland; u, urinary tube. After PACKARD. 



body segments is nearly the same, the legs and claws are essentially 

 alike, and cerci and paired abdominal stylets are present in the two 

 genera, not to mention the correspondences of internal organization. 

 Indeed, it is highly probable, as Packard maintained, that the most 

 primitive insects, Thysanura (and consequently all 

 other insects), originated from a form much like 

 Scolopendrella. A singular thysanuran, Anajapyx 

 vesiculosus (Fig. 7), has been discovered by Silvestri, 

 who regards it as being in many respects the most 

 primitive insect known, combining as it does char- 

 acters of Symphyla, Diplopoda and Campodea. 



Silvestri discovered a peculiar arthropod, Acer- 

 entomon doderoi for which he made a new order 

 Protura. Berlese added two genera to this order, 

 namely, Eosentomon and Acerentulus; and according 

 to good authority Protapieron indicum Schepotieff 

 belongs to the former genus. Silvestri, followed 

 by Borner, put Protura among Apterygota; but 

 Berlese, who grouped these forms under the name 

 of Myrientomata, found that they had myriopodan 

 as well as insectean affinities; and Rimsky-Kor- 

 sakow argues that Myrientomata cannot be rightly 

 regarded as insects, but logically constitute a class by themselves; and 

 that this class does not form a direct link between myriopods and 

 insects, but that all these groups came from the same ancestral stock. 



FIG. 7. Anajapyx 

 1'csicnlosus. Length, 2 

 mm. After SILVESTRI. 



