86 



THE PALEONTOLOGICAL DATA 



Fig. 74. — Homothetus fossilis 

 (After Scudder). 



here are reproduced from Plate VII of Mr. Scudder's 'Pretertiary Insects'). 

 A glance at these figures will convince the reader that the insects of the 

 Devonian times varied greatly in the structure of their wings. For these 



three insects differ as much from each 

 other as do the more generalized mem- 

 bers of widely separated orders of 

 living insects. Evidently, compara- 

 tively high specializations in widely 

 different directions had been attained 

 already at that early time. But the 

 point to which we wish to call especial 

 attention is that, of the three better-preserved Devonian insects, one 

 {Xenoneura) had but few wing-veins. And when we consider the slight 

 amount of data that we have, the numerical preponderance of the many- 

 veined type has no significance. 



"It is easy to conceive of the development of the wings of all living 

 insects from forms allied to Xenoneura, by the different methods of speciali- 

 zation which we have pointed out ; for it will be seen that the wing of this 

 insect closely resembles our hypothetical type. And we can say, therefore, 

 that the paleontological evidence does not contradict the conclusions drawn 

 from a study of the ontogeny of living forms." 



The time has now come when we can present the paleontological data 

 bearing on this subject much more in detail than was possible at the time 

 the above paragraphs were written ; for since then the great work on fossil 

 insects by Handlirsch ('o6-'o8) has appeared. In this work there is 



Fig- 75- — Platephemera anliqua (After Scudder). 



brought together and systematized in a masterly manner what was known 

 regarding Paleozoic insects at the time the book was written; and the most 

 excellent figtires accompanying this work enable us to see clearly what was 

 the characteristics of the wing-venation of the oldest insects whose remains 

 have been found. 



