1909.] NATURAL SCIENCES OF PHILADELPHIA. 481 



acutely fissate mesad with a pair of acute finger-like lobes bordering 

 the same. The supra-anal plate, which is visible ventrad of the 

 incision of the abdominal segment, is acute-angulate. The cerci 

 are slender, tapering, nearly straight, the apical portion substyli- 

 form, the apex rather blunted, the usual tooth on the internal margin 

 is hidden by the supra-anal plate when the cerci are together. The 

 subgenital plate has a small median rectangulate emargination, the 

 styles being extremely short. 



The measurements of the two specimens are as follows: 



Length of body, 22 mm. 21 mm. 



Length of pronotum, 5.5 " 5 " 



Greatest caudal width of pronotum, . 3.5 " 3.8 " 



Length of exposed tegmen, 2.5 " 



Length of caudal femur, 18.5 " 20.5 " 



Length of ovipositor, 19.5 " 



It is seldom that one can take exception to any portion of the excel- 

 lent work of Caudell in his study of the North American Decticinse, 

 but to his assignment of this name to the synonymy 21 we are compelled 

 to disagree. No actual comparison was made, as far as we can learn, 

 of Scudder's type of E. albofasciata and that of gracilis, and specimens 

 examined at different times may be considered the same when real 

 differences exist. The characters given by Rehn for separating 

 gracilis from albofasciata hold true in the material before us, and as 

 far as memory serves the type of gracilis was similar to the one in 

 hand, which is undoubtedly adult, although Caudell assumed it to be 

 immature. The bars on the head, pronotum and abdomen are broader 

 in this form than in a number of New Mexican immature individuals 

 of albofasciata, the size is less than that of Scudder's type and the caudal 

 femora appear to be slenderer ana are considerably longer in proportion 

 to the ovipositor. The immature specimen from Phoenix, Arizona, 

 which Caudell says is similar to the type of gracilis, is probably the same 

 as the Cottonwood specimens, as it is quite probable that one form is 

 limited to the Eastern Desert or Chihuahuan Tract and the other to 

 the Western Desert or Sonoran Tract. 



The type locality of E. gracilis is Bill Williams Fork, Arizona. 



Idiostatus sequalis Scudder. 



A single female of this species was taken in the Arroyo Seco at 

 Pasadena, August 1, while two males, one adult and the other not 



2l Proc. U. S. Nat. Mus., XXXII, p. 339. 



