No. 625] HIE EVOLUTIOX OF ARTHROPODS 



167 



crease in tlie number of segments (from nine to twelve 

 in the abdomen) comparable to tlie increase of segments 

 in the ''Myriopoda," so that Tothill's statement that 

 ''in the Hexapoda numerous investigations have shown 

 the segments arise only diu-ing the egg stage" does not 

 hold in the case of the Protura. There is also one other 

 point in Tothill's paper which niiglit easily lead to error 

 unless properly explained: namely, that his discussion of 

 the nature of the appendages of the abdomen in a 

 "larval" Sterwdictya is based upon a figure taken fi-om 

 Handlirscli's book, the sui)i)Osition being that it i'0])re- 

 sonts the restoration of an actual fossil larva, whorcis in 

 reality the figure is purely a figment of llandliisch's 

 imagination, for no known insects have })iramous ab- 

 dominal legs, and even the supposedly l)iramous condition 

 of such specialized structures as the maxilhr of insects is 

 now thought to be a secondarily ac(|uired feature, and not 

 a retention of an originally birnmons coiidilion ( I'orra- 

 dale, 1917). TothilTs Miguvstion i.f a (Icrivalioii of 

 winged insects directly from Chilopoda (which rcprocnt 



develoimient) withont icfnvncc 1.. the a) •Irryu'otan forms 



winged insects from a jttcryuoian l'o)'iii> without having 

 any of the advantages oT the latter h\ ).(,tli('<is. and if 

 the latter is untenable, the idea of derivinu winded iii-ccts 

 from chilopods is infinitely more so I 



Despite the fact that trilobites are on a diveraent 

 branch leading away from the main line of insectan de- 

 velopment [i. c, leading off to the arachnoid develop- 

 ment) TTandlirsch, !{)()(), would derive winged insects 

 directly from t i-ilol.ites. wholly iu-norin- the A])1("rygota. 

 Syniphyh,. Tanai.hicca. and all of the other analoniieally 

 inteniKMlinle forms wiiirh wouhl he exactly on a par witli 

 an allenipl to derive tlie "yor<li<-" race ..f men <lirectlv 



ing to the (leveh)pniei!t of the linnian t>pe) wlioilv io„or- 

 ing the Mongolians. An>traIoi(l>. X(>anderthaloids, 



