June-Sept, 1919.] DAVIS : ClCADAS. 181 



In the table for the separation of species the natural sequence 

 could not be followed in every instance, but we hope that it will serve 

 to identify the members of this difficult group. In order to study 

 these Cicadas the specimens should be spread so that the venation, 

 the character of the basal cell of the fore wing and the color of the 

 basal membranes can be seen. If the wings on one side, preferably 

 the left, are expanded, it will suffice. Cicadas dry very quickly on 

 the stretching board and freshly captured individuals need remain 

 thereon only about a week, and those that have been relaxed in a 

 softening box a still shorter time. In Tibiccn, Cacama and most of 

 the other genera of North American cicadas the uncus is withdrawn 

 by the insect into the abdomen, but in Okanagana, Tibicinoid.es, 

 Clidophlcps and Platypodia it is always exposed. Often it can be 

 fully examined without changing its position, but if the end be bent 

 downward and concealed by the valve, the uncus should be lifted up- 

 ward when the insect is mounted on the stretching board. A portion 

 of a match can be inserted with a forceps between the uncus and the 

 valve until the. parts are dry, or the uncus may be simply lifted up 

 with a pin. 



I have received important material from the following named 

 persons; other acknowledgments are made in connection with the 

 specimens recorded: 



Dr. E. D. Ball, Dr. J. Chester Bradley, Prof. A. C. Burrill, Dr. 

 R. H. Beamer, Prof. W. H. Brittain, Prof. Robert A. Cooley, Alonzo 

 C. Davis, Emerson L. Diven, George P. Engelhardt, Prof. Frederick 

 M. Gaige, Edmund H. Gibson, Morgan Hebard, Miss Esther P. Hew- 

 lett, Otto Huellemann, Prof. S. J. Hunter, Charles W. Johnson, Frank 

 M. Jones, Clarence H. Kennedy, Warren Knaus, Dr. H. H. Knight, 

 J. N. Knull, E. R. Leach, Prof. A. L. Lovett, Miss Mell McGill, Dr. 

 W. M. Mann, P. W. Mason, George A. Moore, Dr. Albert P. Morse, 

 Howard Notman, Miss Edith M. Patch, Prof. Rufus H. Pettit, Col. 

 Wirt Robinson, Charles Schaeffer, Prof. H. C. Severrin, Ernest 

 Shoemaker, Dr. Henry Skinner, Tom Spalding, Prof. L. M. Stohr, 

 Prof. Myron H. Swenk, Edward P. Van Duzee, Prof. H. F. Wick- 

 ham, John Woodgate and Prof. Wm. S. Wright. 



