A CONTRIBUTION TOWARD A MONOGRAPH OF THE HO- 

 MOPTEROUS INSECTS OF THE FAMILY DELPHACID^ 

 OF NORTH AND SOUTH AMERICA. 



By David L. Crawford, 



Of Stanford University, California. 



INTRODUCTION. 



The family Delphacidas was until quite recently and, in fact, by 

 some authors, is yet considered as a subfamily of the larger group 

 Fulgoridse. By most students now, however, it is separated from its 

 near relatives as a distinct family, chiefly on account of the large, 

 movable spur, or calcar, at the base of the posterior tibias. 



The most noticeable characteristic of the group as a whole is its 

 homogeneity in general aspect and appearance. There are a few 

 characters which are constant enough in subgroups to serve as diag- 

 nostic characters, and there are others which are too variable to 

 serve that purpose. Some of the latter have, however, been used 

 by many of the previous students with the result that genera and 

 species have multiplied beyond reason and confusion has more and 

 more crept in. This latter fact has been reahzed more strongly as 

 my work on the group has progressed, and it has at last become 

 necessary to rearrange the classification of the genera to some extent 

 in order to avoid much of the prevalent confusion. 



At the suggestion of Prof. C. F. Baker, of Pomona College, Clare- 

 mont, Cahfornia, the task of working over several collections of speci- 

 mens of this family and naming the species was undertaken some 

 months ago. His own collection of over 2,000 specimens, together 

 with the United States National Museum collection of a still larger 

 number, many of which, also, had been collected by Professor Baker, 

 were placed before me for study. My original purpose, of course, 

 was to classify the specimens before me according to the then ac- 

 cepted basis of classification. Much of the material had already been 

 named authentically or else placed in the genus or subfamily where 

 it would naturally fall. In the United States National Museum 

 material were some paratypes and cotj'pes. 



Proceedings U. S. National Museum, Vol. 46-No. 2041. 



657 



