RESULTS OF PAL^ONTOLOGICAL RESEARCH 37 



tions. As fundamental types we regard those of the 

 first individuals which have become known to us. That 

 is perfectly correct if at least the first representatives 

 are few and all similar as between themselves, and 

 if it can be accepted that precisely those individuals 

 formed, in fact, the starting-point of later forms (species 

 and genera). In that case it is clear that one type, 

 originally confined to one or a few species, becomes 

 varied or differentiated. 



With the numerical increase of the individuals both 

 animals and plants naturally incur the necessity of 

 dividing their resorts or habitats, they occupy different 

 elevations in valleys or on the mountains, deeper or 

 shallower water, and more humid or drier climates, etc. 

 This gives the impulse to varied specialization. The 

 type itself becomes varied by the varied specialization 

 of the separated individuals. 



The phylogeny of the Insects may be studied more 

 in detail to elucidate the above. For this group we 

 possess A. Handlirsch/s great work, ' Die f ossilen Insecten 

 und die Phylogenie der rezenten Formen/ l a compre- 

 hensive presentation and consideration of the whole 

 of the discoveries so far made. 



The oldest insects, the Palaeodictyoptera (Fig. 5), 

 appear in the lower strata of the very productive 

 Carboniferous system. They were of considerable size, 

 many of them as long as the hand or even the arm, 

 with six legs and four or six wings. The vein system 



1 Vol. II, Leipzig, 1906-1908. An exposition by Handlirsch himself 

 appeared in Die Umschau, 1909, p. 588. 



