1920] Crampton — Genitalia of Male Hymenoptera and Other Insects 43 



ninth abdominal segment form the gonopleurites "pp," while the 

 sternite of the ninth segment usually forms the hypandrium "ha" 

 or plate belown the genitalia of the male. WTien the cerci "ca" 

 are present, they are borne on a region representing the union 

 of the paraprocts of the eleventh segment ("pr" of Fig. 12) fused 

 with the tenth tergite, as in Fig. 17, and this in turn may unite 

 with the ninth tergite. In the lower insects a pair of styli "s" 

 or gonopods is attached to the posterior margin of the hypandrium 

 (ninth sternite), or plate below the genitalia of the male. In 

 higher insects a pair of styli (gonostyli, or gonopods) forms the 

 outer ventral pair of claspers "s" between which the penis valves 

 "pv" or phallus are situated. The only structures which one can 

 compare with these gonostyli or gonopods in larval insects, are 

 borne on the tenth sternite (Fig. 6, "s") as in larvae of Trichoptera, 

 certain sawflies, etc. 



From a study of the wing veins, and head region, I formerly 

 maintained that the Homoptera (and Hemiptera) are somewhat 

 more closely related to the insects grouped about the Psocidse 

 than to those grouped about the Neuroptera. The thoracic 

 sclerites of the Homoptera, however, are very like those of the 

 Neuroptera, and the genitalia of the male Fulgoriadse, Psyllidse, 

 etc., here studied would bear out the view that the Homoptera 

 are more closely allied to the Neuroptera and other Neuropteroid 

 insects such as the Mecoptera, Lepidoptera, etc. The nature of 

 the genitalia of the Strepsiptera would tend to confirm the conten- 

 tion that these insects are quite closely related to the Homoptera, 

 such as the Psyllidse, etc., although they show considerable resem- 

 blance to the Mecoptera and other Neuropteroid insects. The 

 genitalia of the Diptera are like those of the Mecoptera and 

 Trichoptera, and the lower Trichoptera are very similar to the 

 lower Lepidoptera, as one would expect from a study of other 

 features than the genitalia. The genitalia of the sawflies are as 

 much like those of the Mecoptera as any insects, although they 

 exhibit some resemblances to the genitalia of the Diptera also. 

 In the main, the study of the genitalia of the higher insects would 

 serve to substantiate the evidences of relationships furnished by 

 other anatomical structures, and it would therefore be in harmony 

 with the views concerning the interrelationships of the insects 

 related to the Neuroptera, recently published in the Transactions 

 of the Entomological Society of London (Crampton, 1919a). 



