284 



HALF HOURS WITH INSECTS. 



[Pacicard. 



affinity, in order tliat tliese two series may be virtually 

 brought together ; while the successive forms in the several 

 families shall afford us some conception of the larger cate- 

 gories these minor groups foreshadow. Such a group Pro- 

 fessor Agassiz * has pointed out in the class of Selachians, 

 which combine the characters of all the other classes of 

 fishes existing during the same period, and also, by their 

 being the earliest in time, afford what he calls j^foj^hetic types 

 Fig. 220. Fig. 221. 



Lepisma. Campodea. 



of all the coming classes of vertebrates. The former case 

 affords what he calls synthetic types." 



In endeavoring to show that a similar synthesis as marked 

 as in the fishes or reptiles, or other groups of animals, occurs 

 in the different nonropterous families of insects, the case of 

 the Lejnsma (Fig. 220, L. quadrlseriata) or bristle tail, may 

 be cited, which is closely allied to the Campodea (Fig. 221), 



* Essay on Classification. 



28 



