RELATIONS OF INSECTS TO OTHER ARTHROPODA 21 



multiarticulate appendages of Lepisma, etc., and of the forceps of 

 Japyx. In those of Scolopendrella, we have found the large duct 

 leading from the voluminous silk-gland, a single large sac extend- 

 ing forwards into the third segment from the end of the body (Fig. 

 15, s. gl). Other points of resemblance, all of which he enumerates, 

 are the slight differences in the number of trunk-segments, the pres- 

 ence in the two groups of the abdominal "false-legs" (parapodia), 

 the dorsal plate, and the mouth-parts. As regards the latter, Grassi 

 affirms that there is a perfect parallelism between those of Scolopen- 

 'drella and Thysanura. To this point we will return again in treat- 

 ing more especially of those of the Symphyla. Finally, Grassi 

 concludes that there is " a great resemblance between the Thysanura 

 and Scolopendrella." He, however, believed that the Symphyla 

 are the forerunners of the myriopods, and not of the insects, his 

 genealogical tree representing the symphylan and thysanuran phyla 

 as originating from the same point, this point also being, rather 

 strangely, the point of origin of the arachnidan phylum. 



Haase (1889) regarded Scolopendrella as a myriopod, and Pocock 

 (1893) assigned the Symphyla to an independent class, regarding 

 Scolopendrella as "the living form that comes nearest to the 

 hypothetical ancestor of the two great divisions of tracheates. 

 Schmidt's work (1895) on the morphology of this genus is more 

 extended and richly illustrated than Grassi's, his method of research 

 being more modern. He also regards this form as one of the lower 

 myriopods. 



In conclusion, it appears to us that, on the whole, if we throw out 

 the single characteristic of the anteriorly situated genital opening, 

 the ovarian tubes being directed toward the end of the body (Fig. 15, 

 cvd, ov), there is not sufficient reason for placing the Symphyla 

 among the Myriopocla, either below or near the diplopods. This 

 is the only valid reason for not regarding Scolopendrella as the 

 representative of a group from which the insects have descended, 

 and which partly fills the wide abyss between Peripatus and insects. 

 With the view of Pocock, that both insects and myriopods have 

 descended from Scolopendrella, we do not agree, because this form 

 has so many insectean features, and a single unpaired genital open- 

 ing. For the same reason we should not agree with Schmidt in 

 interpolating the Symphyla between the Pauropoda and Diplopoda. 

 In these last two progoneate groups the genital openings are paired, 

 hence they are much more primitive types than Scolopendrella, in 

 which there is but a single opening. It seems most probable that 

 the Symphyla, though progoneate, are more recent forms than the 



