Psyche 



[June 



and are also related to the Hymenoptera. The line of develop- 

 ment of the Diptera merges with that of the Mecoptera, and the 

 line of development of the Lepidoptera merges with that of the 

 Trichoptera as all of these are traced back to the common neurop- 

 teroid stem. The Trichoptera are probably a little more closely 

 related to the Neuroptera than to the Mecoptera, but their line of 

 descent branched off from the common neuropteroid stem very 

 near to the point of origin of the mecopteron line of development 

 on the same neuropteroid stem. There are some reasons for re- 

 garding the Mecoptera as the stem forms from which the lines of 

 development of the Diptera, Trichoptera and Lepidoptera have 

 sprung; but the Neuroptera are on the whole as near as any, to 

 the ancestral forms from which all of these insects are descended. 



Abbreviations. 

 a. = Adanal process or ossicle pf . = Prescutal fontanelle. 



po. = Posttergite. 



prt. = Pretergite. 



ps. = Parascutellum. 



psc. = Prescutum. 



psl. = Postscutellum. 



pt. = Parategula. 



ptg. = Postalare or pleurotergite. 



s. = Suralare. 



(adanale) . 

 j.=Juxtategula. 

 m. = Median ossicle (niedip- 



terale) . 

 ma. = Membranous area of post 



scutellum. 

 ms. = Middorsal suture, 

 mt. = Meditergite. 

 n. = Notopteral ossicle (notop- sc. = Scutum. 



terale) . si. = Scutellum. 



pa. = Prealar bridge (prealare) . so. = Scutal organ, 



t. = Tegula. 



Explanation of Plate II. 



Fig. 1 . Mesonotum and wing-base of the Hymenopteron Ceph- 

 aleia. 



Fig. 2. Mesonotum and wing-base of the Trichopteron Neu- 

 roma. 



Fig. 3. Mesonotum and wing-base of the Mecopteron Bittacus. 



Fig. 4. Mesonotum and wing-base of the Lepidopteron 

 Phassiis. 



Fig. 5. JMesonotum and vring-base of the Neuropteron Nemop- 

 tera. 



Fig. G. Mesonotum and wing-base of the Dipteron Tipula. 



