Proceedings 245 



ern orders Orthoptera, and Coleoptera; the Hemipteroidea give us the 

 Hemiptera and Homoptera; the Neuropteroidea have split up into the 

 orders Neuroptera, Hymenoptera, Lepidoptera, and Diptera. Adopting 

 Latreille's terms for the first and the third, and that of Fabricius for 

 the second we have the three series Elytroptera, Rhynchota and Gym- 

 noptera. 



The three lines of modifications are also indicated by their habitat 

 as one of the underlying causes. The Elytroptera are ground insects, 

 hence their modification of the front wings for protection. The Rhyn- 

 chota are semi-parasitic on plants, hence their main line of modifica- 

 tion is seen in the formation of the jointed beak for piercing and 

 sucking. The suctorial Hemiptera existed long before the suctorial 

 trophi of the other orders had come into existence, and is a more 

 primitive type than those of Diptera. The Gymnoptera are mainly ar- 

 borial or aerial in habitat, the birds among the insects, hence their 

 peculiar modifications of the wings so distinct from the first. 



There are also some ontogenetic facts that point the same way. 

 The embryonic membranes of primitive insects were temporary organs 

 and did not persist to the time of hatching. Blastokenesis is charac- 

 teristic of primitive Orthoptera, Hemiptera and Neuroptera. It is only 

 in the more modern orders that one or both of the membranes persist 

 to the time of hatching. Based upon these and other facts that await 

 a future and more extended treatment, the following arrangement of 

 the orders of insects into series was proposed. 



Series Elytroptera. Ground insects; wings dissimilar, front pair 

 elytra, hind pair membranous and folded when at rest, of primary 

 importance in flight; trophi mandibulate. Orders: 



Orthoptera, s. 1. 



Coleoptera. 

 Series Rhynchota. Semiparasitic; trophi forming a jointed 

 rostrum adapted for piercing and sucking. The sucking trophi already 

 present at the time of hatching. Wing modification of secondary im- 

 portance in comparison with the Elytroptera, and Gymnoptera. Meta- 

 morphosis gradual. Orders: 



Hemiptera. 



Homoptera. 

 Series Gymnoptera. Arborial or aerial insects; the two pair of 

 wings similar, the front pair of primary importance in flight; the hind 

 pair often reduced or lost. Trophi mandibulate in Neuroptera; suctor- 

 ial in the Hymenoptera, Lepidoptera, and Diptera. Orders: 



Neuroptera, s. 1. 



Hymenoptera. 



Lepidoptera. 



Diptera. 

 The recognition of a larger number of orders, as the 17 of Brauer, 

 or in a probable still greater division of the future, in no way invali- 

 dates the recognition of three series in place of two, but brings out a 

 number of additional facts in its favor. 



