152 TRANSACTlOi^S OF THE [1892 



of both these species, including both sexes, I am urged, 

 against my former convictions, to accept this as a dis- 

 tinct species. A full knowledge of the life history of 

 this insect may hereafter show that it is only a race of 

 the former, but until such proof is adduced we are not 

 in a position to unite the two forms in one species. 



4. C. superba Fitch, First Eeport N. Y., 1856, p. 41. 

 This is also a variable species, in which the wing- 

 covers are more or less suffused with brown near the 

 tips, and the apical nervures sometimes bordered v\^ith 

 still darker brown. It has been taken in Indian Terri- 

 tory, Central Texas, and in the region of the Hio Pecos, 

 New Mexico. The structural elements agree closely 

 v/ith those of C. tibicen, and the pattern of marking is 

 just such as we might expect to find in a weak race of 

 the species in which the deep colors have failed to be 

 filled out. The partial absence of dark color on the body 

 seems to be in a degree compensated by the transfer of 

 that color to the wing-covers and wings. Can the alka- 

 line soils of its habitat aid in producing this modification 

 of color in the superficial integuments? 



5. C. dorsata Say, Journ. Acad. Philada., v. IV., 1825, p. 



331, No. 3, Cicada robertsonii Fitch, First Report 



N. Y., 1856, p. 41. 

 This species inhabits the prairies and plains from Dal- 

 las county, Iowa, and eastern Nebraska to southern 

 (not coastal) Texas. It is not uncommon in Colorado 

 and New Mexico, and it extends east across the western 

 borders of Missouri and Arkansas. Varieties of this 

 species apparently approaching C. marginata Say occur 

 in Texas and New Mexico ; and a variety of the latter 

 from North Carolina possesses many of the structural 

 features of C. dorsata. 



