Dec, 1917-] Davis: Sonoran Cicadas. 209 



first and second cross veins slightly infuscated. The basal cell of each fore 

 wing nearly clear, but blackened along the anterior margin. The flaps of 

 both fore and hind wings are gray in color. Beneath pruinose, black about 

 the eyes, where there are some long, silken, white hairs. The transverse 

 rugse are yellowish and somewhat blackened where they join the shallow 

 frontal sulcus. The legs are chocolate-colored with lighter spots and dashes, 

 the hind pair being lighter colored than the other two pair. The opercula 

 are pruinose, the lower extremities of the inner margins not quite touching, 

 and the ends rounded. The ventral segments are dark chocolate-colored, 

 central ones being lighter posteriorly. The last segment is rounded at the 

 extremity and the valve is black. The external parts of the genitalia choco- 

 late-colored and black. 



Measurements (in Millimeters). 



Male Type 



Length of body 24. 



Width of head across eyes 9.5 



Expanse of fore wings 70. 



Greatest width of operculum 5. 



Greatest length of operculum 4.5 



In addition to the type four other males were collected on rocky 

 slopes at the same time and place. Mr. Knight says : " This form has 

 a most unusual song; resembles loud rasping of an Acridid grass- 

 hopper; rasps and intervals about equal." This species resembles in 

 form, in color, and in shining appearance the much smaller Tibicen 

 arisona from the Santa Rita Mts., Arizona, described and figured in 

 the Journal N. Y. Ento. Soc, March, 1916. It also resembles some- 

 what in form, though not in color, the figure of Cicada psophis in 

 Biol. Centr.-Amer., but it does not agree with Walker's original de- 

 scription. 



I take great pleasure in naming this insect after Mr. Harry H. 

 Knight, who spent much time in collecting cicadas for me, as the 

 records in this paper will attest, and who has also sent to me many 

 other specimens on former occasions. 



Tibicen delicata Osborn. 



Laguna, Texas, Nueces River, July 2, 191 7, on Bignonia, the desert 

 willow, 5 males, i female, and Sheffield, Texas, Pecos River, July 4, 

 191 7, all collected by Mr, Knight. 



This species was figured on plate VI, fig. 2, Journal N. Y. Ento. 

 Soc, March, 1916, the illustration being made from one of the type 



