70 THE GENUS CORYTHUCHA 



be given the most weight: position and shape of hood and the 

 height of its crest, the size of its areoles, the constriction on the 

 hood, and also the relative height and length of the median carina. 

 Besides these he recognized the following: size and form of the 

 cells of the elytra, the armature, the rostral groove, the length 

 of the antennae and rostrum. He at one time stated that the 

 male characters were of no use in Corythucha and that he could 

 find but little difference in the claspers. In a number of descrip- 

 tions of new^ forms which have been recently published, consid- 

 erable stress has been laid upon the comparative length of the 

 first and second antennal joints. The author can not see the 

 justification of the use of such characters in separating the species, 

 as they are "hair-splitting," and as it has been frequently noted 

 the comparative lengths of the first and second joints will vary 

 considerably^ with the antennae of the same specimen. General 

 size and intensit}' of color will also vary to a greater or lesser 

 degree within the species. 



The comparative measurements of the pronotal hood and 

 median and lateral carinae are found to be very reliable and 

 stable and, with the relative size of the areoles of hood and 

 paranota and color pattern of elytra, form quite sufficient char- 

 acters for specific diagnosis. In the key to the species and in 

 their descriptions a sharp difference is made in the phrases, 

 "hood ... as high as median carina" and'' height of hood." 

 The latter applies to the measurement of the hood alone, taken 

 by a line perpendicular to the line of the base of the hood and 

 extending to its crest, while the former is a measurement of the 

 distance from the top of the median carina to the line of the crest 

 of the hood extended and parallel to the line of the body. 



In establishing a key to the species, specimens of every species, 

 and with the majority of species the types, have been examined, 

 the key resulting from a direct study of the specimens rather than 

 relying to any extent upon descriptions which in several instances 

 are meager. A redescription of nearlj^ every species has been 

 necessary. 



The species are here listed in what appears to be the logical 

 natural order, which is based upon the color pattern of the elytra 

 and general development of the pronotal hood. They may be 

 considered as grouped into five distinct classes, typical of which 



