2 Bulletin of the Brooklyn Entomological Society Vol. XVI 



or group in which the investigator specialized. F. N. Pierce, a 

 British lepidopterist, has probably contributed more to our knowl- 

 edge of the systematic value of Lepidopterous genitalia than any 

 other author. The systematic schema of terminology is adapted 

 . from his two works, " The Genitalia of the Noctuidse " and " The 

 Genitalia of the Geometridse." 



The primary object of this paper is to homologize these two 

 systems of nomenclature by a comparative study of the most 

 primitive family of the order Lepidoptera, namely the Hepialidae. 



The male genitalia of many Neuropteroids, Trichoptera and all 

 available families of Lepidoptera have been examined in connec- 

 tion with the preparation of this paper, but only the Hepialidse are 

 figured, for they best accomplish this purpose. 



Terminology 



The abdomen of the typical lepidopteron consists of eleven 

 segments designated by the morphologist as somites, the dorsal 

 chitinized portion being called the tergum and the ventral chitin- 

 ized portion, the sternum. The genitalia proper are formed by the 

 telescoping and anastomosing of the last four abdominal somites 

 (8, 9, 10, ii) accompanied by a structural modification of their 

 respective appendages (I, II, III, IV) according to function. In 

 the Hepialidse this telescoping has taken place to a much less 

 extent than in any other of the Lepidopterous families, the somites 

 retaining a more generalized condition in regard to the shape of 

 their terga and sterna and the relative positions of their re- 

 spective appendages. 



In all higher Lepidoptera, somites 1-7 possess a pair of spiracles 

 located on the lateral margins of the sternum ; in the Hepialidas 

 somite 8 also retains a well-developed pair of spiracles. 



Those structures constituting the genitalia proper may be de- 

 scribed and homologized as follows (see Fig. i) : 



Somite 8: 



Tergum: A simple unmodified chitinous plate. 



Sternum-: A small rectangular ventro-cephalic plate and a 



broader curved, invaginated V- or U-shaped portion, the Vin- 



