xxii S}\VOFS/S. 



parts of Mtisca domestica, 265. Characters of larvae, 266. Light 

 thrown on the subject of the systematic position of the Diptera 

 by Weismann's observations on the development of the Musci- 

 d?e, and M. Ganin's views on the post-embryonal development 

 of insects, 266. Qistridae, 267. Thoracic region uncovered by 

 abdomen, 267. Larvae parasitic on mammals, 267. Life-his- 

 tory of CEstriis ovis, 267. Modifications of structure peculiar to 

 different species of bot-flies, 268. Verrill on Gastrophilus equi, 

 268. Pulicidae, 268. Semi-parasitic habits of the adult, conse- 

 quent modification of structure, 269. Loss of power of flight 

 compensated for by increased power of leaping, 269, 270. Diet 

 of the larvae, 270. Pupipara, 271; significance of term, 271. 

 Degraded structure of the Braulinidae and Nycteribidae, 271. 

 Hippoboscid^e, 272. Adaptations of legs, 272, Development 

 of Hippobosca equina, 273. General remarks on the classifica- 

 tion of the Diptera, 273. Larvae farther removed from the Thy- 

 sanuriform type than those of any other group, 273. The absence 

 of thoracic legs in larvae which live in situations that seem to 

 demand them, a peculiarity inherited from an ancestral form 

 whose larvae had lost the thoracic legs, 274; inflexibility of larvae 

 sufficient to show a wide gap between existing Diptera and other 

 orders of insects, 274. Extreme specialization of the adults in 

 Diptera, 274. 



GENEKAI. REMARKS. 



In the first series of orders the direct mode of development 

 unites the Thysanuriform larva closely with the adult stages; 

 traces of this close connection are shown by retention of cer- 

 tain primitive characters, 275. Mouth parts of first series 

 adapted for biting; suctorial mouth parts of Hemiptera are 

 exceptional, 275; primitive form of larva retained in Hemip- 

 tera, 275. Complicated modes of development in second series 

 of orders, 275, introduction of secondary larval stages, 275; 

 these stages degraded modifications of the Thysanuriform larva, 

 275. Pupa stage of second series identical with that of first 

 series, with the exception that it is incapable of motion, 276. 

 Use of the terms " Ametabola " and " Metabola," 276. Voracity 

 of larvae of second series of orders, 276; fatty accumulations 



