ENTOMOLOGY 



Scolopendrella, now placed either among Diplopoda or else 

 in a class by itself, Symphyla, presents a remarkable combina- 



FIG. 7- 



Section of Scolopendrella immaculata. b, brain; c, coxal gland; f, fore intestine; 

 h, hind intestine; tn, mid intestine; n, nerve chain; o, opening of silk gland; od, 

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



tion of diplopodan and insectean characters. Scolopendrella 

 (Fig. 6) and the thysanuran Campodea have the same kind 

 of head, with its long /monili form antennae, and agree in the 

 general structure of the mouth parts ; 

 the number of body segments is nearly 

 the same, the legs and claws are essen- 

 tially alike, and cerci and paired abdom- 

 inal 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, Thys- 

 anura (and consequently all other in- 

 sects), originated from a form much like 

 Scolopendrella. A singular thysanuran, 

 Anajapyx vesiculosus (Fig. 7), has 

 lately been discovered by Silvestri, who 

 regards it as being in many respects the 

 most primitive insect known, combining 

 as it does characters of Symphyla, Diplo- 

 poda and Campodea. 

 The following diagram (Fig. 8) expresses very crudely one 

 view as to the annelid origin of the chief classes of Arthro- 

 poda. 



Anajapyx vesiculosus. 

 Length, 2 mm. After 

 SILVESTRI. 



