66 TETTJG/D.£ OF NORTH AMERICA 



meant in his description. The measurement of male and 

 female he gives as follows: 



Length of body, ,j 5, 7-9 mm.; jjronot., 7.5-9 mm.; post, 

 fem., 4.5-6 mm. 



Tettix cristatus, Bol., Essai, Ann. Soc. Ent. Belg. XXXI'., 

 257, 260 (1887). 



In the following group are some which present the most 

 suggestive problems of variation; there is evidence of the recent 

 origin of many changes in structure. The tendency to vary 

 is inherent in all the forms, the line of demarkation not easily 

 drawn between species, but it is clearly apparent from an 

 examination of a considerable series from distant and inter- 

 mediate localities that appreciable changes in structure are 

 taking place through the reaction of the organisms on their 

 environment; varieties and species are being formed moder- 

 ately rapidly, and some of the forms have not yet attained the 

 degree of specialization to which they are trending. The 

 descriptions of the species give a composite conception to 

 the mind, the variations being of such wide range as to baffle 

 separate description of each individual phase. The differ- 

 ence between the extremes of the gramilatus and the arenosus 

 groups is very wide, approaching separate generic rank. 



DISPOSITION OF SPECIES. 



GRAN'ULATUS GROUP. 



1. Median carina of pronotum more or less distinctly 



elevated, percurrent; dorsum transversely tectiform. 



2. Body slender, pronotal process posteriorly extenuate; 



vertex viewed from above obtuse angulate. 



granu/ntus, Scudd. 

 2A. Pronotal process and wings more or less abbrevi- 

 ated, g. variegatus, var. n. 

 2. 2. Dorsum between the shoulders wider; apical process 

 and wings shorter ; scapular area higher over the 

 outer fourth of elytra; face broader, ampliate. 



iitcurvatiis, Hanc. 



