343 



Length, exclusive of genital-cover, 19 millimeters; expanse of wings, 

 51 millimeters ; width of base of prouotum, 9 millimeters. 



Collected in the vicinity of Denver City, Col., by C. Thomas. 



This species is closely related to G. rimosa, Say, and must be referred 

 to the same subdivision of the genus. It differs most from that species 

 in the shape of the head, sides of pronotum, and form of genital pieces. 

 Nevertheless, I do not doubt that, when all the heteromorphs of C. rimosa 

 have been sufficiently studied in the regions which they affect, local forms 

 wall be discovered to connect all the extremes into one complete species- 

 cycle. Enough is already known of the influences of soil, physical 

 and chemical agencies, excess or insufficiency of nourishment, and of 

 extremes or sudden emergencies of weather to show us that certain flexi- 

 ble types of insect-life are changed thereby, but which may continue fixed 

 in a particular type in the region where the conditions remain stable. 

 Transportation from one locality to another of a different kind also 

 stamps characters suitable to the changed conditions of life of the species. 



6. C. areolata. 



Cicada areolata, Uhler, Proc. Phila. Acad. 1861, 285. 



Collected in Cache Valley, Utah, by C. Thomas, but previously known 

 from San Mateo, Cal. (A. Agassiz); from Ogdeu, Utah; from Virginia 

 City, Kev. (J. Behreus) ; and from Washington Territory. 



Family MEMBRACTDiE. 



Ceresa, Fairm. 



1. C. diceros. 



Memhracis diceros, Say, Loug's Expedition, appendix, 299. 



Obtained at La Bonte by C, Thomas. This species is very widely 

 distributed throughout temperate North America. 



2. C. hubalus. 



Memhracis hiihalus, Fab., Ent. Syst. iv, 14. 



Common in most parts of the United States. The present specimens 

 were collected in Wyoming Territory by C. Thomas. In Maryland, this 

 species is exceedingly abundant in late summer on the twigs and leaves 

 of the willows growing in damp and wet situations. It varies somewhat 

 in colors, but remarkably in the form of the pronotum. The lateral 

 angles of the jironotum are produced and curved in some; in others, 

 short and blunt; in others, straight and acute; and, in still others, 

 slender, acute, and with a hollowed space in front of the prouotum. 

 Usually, they are almost uniform pea-green ; but varieties occur which 

 are more or less mottled, and marked with rufous or fuscous. 



Lieut. W. B. Carpenter found this species in the vicinity of Eagle 

 Elver, Colorado, in August, 1873, and also in various other parts of 

 Colorado from June to September. 



Enchenopa, Amyot & Serv. 



JS. curvata. 



Memhracis curvata. Fab., Syst. Ehyng. 13, No. 34. 

 Memhracis latipes. Say, Long's Exped. ii, 302, .5. 



One specimen from Eagle River, Colorado, August 29, by Lieut. W, 

 B. Carpenter. 



