298 STUDIES IN AMERICAN TETTIGONIIDAE (oRTHOPTERA) 



The area of intergradation between furcata furcata and typical 

 /. furcifera in the United States comprehends the Rio Grande 

 plain m Texas, and atypical /. furcifera is found further west 

 from the Pecos River in western Texas northward to the vicinity 

 of Fort Collins, Colorado, and westward across the southern por- 

 tions of Utah and Nevada to southern California. This latter 

 material we term atypical /. furcifera since in the form of the male 

 supra-anal plate closer affinity to that race than to /. furcata is 

 shoAvn, but the females have a heavier and larger ovipositor than 

 tj^pical females of either of the above races. It is this character 

 and the somewhat different proportions of this material which we 

 believe indicates the incipient formation of a geographic race. 

 In the northward distribution of this type the ovipositor shows a 

 gradual decrease in size. 



The Pacific coast material from British Columbia to south- 

 central California (Santa Clara County) is perfectly typical of 

 furcata furcata except that in the males the supra-anal plate is 

 very much more decidedly enlarged apically. No other differ- 

 ential characters exist in either sex and we do not consider this 

 material worthy of racial distinction but we do feel that again evi- 

 dence of another incipient geographic race is present. 



It may be noted that the material of /. furcifera from near the 

 Mexican line in the southwestern United States (Chisos Moun- 

 tains, Texas; Chiricahua, Huachuca and Baboquivari Mountams, 

 Arizona and Los Angeles, California), though atypical, approaches 

 that race more closely than does any other material from the 

 United States, but as stated above the ovipositor is heavier and 

 larger and besides the insects are usually large. Referring to *S. 

 paronae it may be seen that, although typically quite distinct 

 from typical /. furcifera, Mexican material of paronae closely re- 

 sembles the material here being discussed, as it is very much 

 like typical /. furcifera but larger and having in the females a longer 

 (but in this case proportionately shallower) ovipositor. The 

 characters separating typical material of the races of this species 

 and its nearest ally, S. paronae, are given in the key. 



This insect varies geographically in size as follows, the teg- 

 minal length in males being given here, as it is approximately 

 the best dimensions for showing such variation smce very little 

 tegminal variation in abbreviation or production is present in 



