groups of insects, the peculiarities of venation did not receive 

 attention until a later date. Van der Hoeven (1828) was pro- 

 bably the first to point out the diñerences in the veining of the 

 wings of different Odonata, and from his time onward there has. 

 been an ever-increasing study of this field. 



It will not be, I hope, an injustice to any of the numerous 

 investigators to credit the greatest advance in our knowledge of 

 the wing-veins of insects to Professors Comstock and Needham, 

 whose Wings of Insects appeared in 1898 and 1899. Speaking 

 as I do on English soil, I trust that I may be pardoned for a 

 slight digression from my subject if I assume to express, on 

 behalf of American entomologists, our deep appreciation of the 

 honour which the Entomological Society of London conferred 

 upon Professor Comstock last November in making him one of 

 its honorary members. 



It is not necessary to linger here on the embr3'ological method 

 which led the two authors to the establishment of the homologies 

 of the wing-veins throughout the class Insecta and of a common 

 nomenclature for the highly diñerent orders. The application 

 of this method to the Odonata led to the realisation of the full 

 significance of the assumption by one wing-trachea during 

 larval life of a position posterior to that which it originally 

 occupied, and the crossing of the radial sector, determined by 

 this trachea, was announced as " a character quite distinctive 

 of this order." The morphology of the arculus, the triangle, and 

 the anal loop was also elucidated. 



The subject was still further illumined by Professor Need- 

 ham in his Genealogie Study of Dragon-fly Wing Venation (1903).. 

 This memoir advanced our knowledge of the homologies of the 

 veins within the order, traced changes in venation from genus 

 to genus, suppUed developmental data for the determination of 

 the values of venational characters in classification, suggested 

 mechanical causes for the peculiarities of wings and veins, and 

 developed ideas as to what constitute generahsed and speciaHsed 

 conditions in these organs. No work on the Odonata within the 

 period of our survey has had a greater influence on other in- 

 vestigators, due partly to the great variety of detail which the 

 venation presents, but chiefly to the underlying method and the 

 novelty of ideas in which the Genealogie Study abounds. 



