32 WILLIAM MORTON WHEELER. 



of the hind wing is very different from that of the fore wing, and 

 the anal lobe is clearly marked off by a deep notch. The head 

 is without a fontanelle, the antennae are long and 3O-jointed, the 

 labrum does not project, the prothorax is large, larger, in fact, 

 than the head, the tibiae have a row of spines along their sides 

 and four spines at the apex. The tarsi are 5 -jointed and fur- 

 nished with a small pulvillus. 



Desneux's study of Mastotermes thus supplies the keystone to 

 a taxonomic arch which students of the lower insects have been 

 building for some time past. The structure is, however, still in- 

 complete, since only the facts of comparative anatomy seem to 

 have been consulted, and due regard for the facts of paleontology, 

 geographical distribution, embryology and ethology must be had 

 before we can accept the derivation of the Termitidae from the 

 Blattidas as established beyond contradiction. As Handlirsch 

 has studied fossil insects extensively, it is probable that he has 

 at least found nothing in paleontology to contradict his theory. 

 In regard to geographical distribution there is no difficulty, but 

 instead a singular resemblance between the two groups of insects 

 in question, inasmuch as both of them are cosmopolitan and, with 

 the exception of a very few species, confined to tropical and sub- 

 tropical countries. In other words, countries which are most 

 favorable to the development of Blattidae also have a rich termite 

 fauna. But how stands it with the embryology and ethology of 

 the Blattidae and Termitidae ? I believe that the views of Hand- 

 lirsch and Desneux are not without some support from these 

 sources also, as I shall attempt to show in the following 

 paragraphs. 



A number of investigators have studied the development of 

 various Orthoptera, including the Blattidae, and Knower ('oo) 

 has furnished us with a valuable paper on the embryology of a 

 termite (Entcnncs). In comparing the development of these in- 

 sects with one another we are struck with the remarkable sim- 

 ilarity between the termite and the Orthoptera, especially certain 

 Saltatoria (Acridiidae and Gryllidae). This resemblance, which 

 was recognized by Knower, is seen in the simple nature of the 

 chorion, the absence of a vitelline membrane, the structure and 

 consistency of the yolk, the great volume of the yolk as com- 



