April. '07] ENTOMOLOGICAL NEWS. 121 



doubt as to the species intended and consequently C. fuh-ula 

 Osborn falls into synonymy. Canicularis Harris is sufficiently 

 well characterized to enable the species to be recognized with 

 certainty. Having thus disposed of or identified all the pub- 

 lished names we are free to name all other forms that are 

 specifically distinct from them. 



Cicada Unnei is proposed for the species which has so long 

 been known as tibicen. 



Cicada sayi is proposed for the form hitherto erroneously 

 known as pruinosa. 



Cicada davisi, so called in honor of Mr. Wm. T. Davis, 

 whose article induced the present critical study, is proposed for 

 a very distinct little species which has been confused with 

 canicularis. 



Cicada similaris is proposed for a Floridan species, close to 

 Ixriccn in general appearance, but widely variant in genitalic 

 structure. 



There are other species under our observation from the 

 U. S. N. M. collection, which will eventually have to be named ; 

 but which we do not describe, partly because of the scant ma- 

 terial at hand and principally because they are quite without the 

 scope set for this study. The genitalia of one of these species 

 from Mexico is figured, pi. Ill, f. 7 and 8, to illustrate the 

 amount of variation displayed by members of the tibicen group. 



There is considerable difference between species in a number 

 of structural details, but most of them are subject to some 

 variation. These differences may be used to good advantage 

 for the separation of species, though in a few cases the variation 

 is so great as to leave almost no definite line of demarcation 

 between closely allied species when only one character is used. 

 For the purposes of specific separation no structures are of 

 more importance than the male genitalia, which in the Cicadids 

 are large, strongly chitinized and easily examined. They are 

 absolutely constant in form, however subtile certain processes 

 may be, and are always to be relied upon. The uncus shows 

 the greatest diversity of form. In the usual type it is broad 

 above, with parallel lateral margins, and from the side is 

 narrow, slightly constricted a short distance from the base, and 



