22 University of Michigan 



form is described above. This I considered a distinct and 

 very peculiar species until recently, when I received through 

 tiie kindness of Professor C. J. Drake a series of specimens 

 containing intermediates which lead indubitably to typical 

 marmorata, through atypical forms of the latter common in 

 every collection, and which fully support the idea expressed 

 by Drake {in litt.), that inforniis and inar)norata are not 

 specifically distinct. Inforniis is not a geographical race, since 

 it occurs in districts as widely separated as Nova Scotia, Colo- 

 rado, and British Columbia, in company with the typical form. 

 The color pattern is essentially alike in all of the specimens 

 examined and is identical with that of typical marmorata, the 

 presence of an intermediate hemielytral band and the trans- 

 verse division of the apical band by a row of pale areoles be- 

 ing characteristic. The intensity of the markings is subject to 

 variation, as usual. The height of the hood, proportions of. 

 hemielytra and their discal elevations, and length of marginal 

 spines all vary, and there are before me various stages in the 

 development of all these structural characters, leading to the 

 extreme variety inforniis. In typical marmorata the hood is 

 frequently twice as high as the median carina, a point which 

 may cause confusion in the use of Gibson's key. 



In explanation of this unusual degree of variability, I would 

 suggest that in the species under consideration we may note 

 the appearance of a distinct tendency toward pterygo-poly- 

 morphism, a phenomenon of wide spread occurrence among the 

 Tingidae but not hitherto observed in the genus Corythucha. 

 Specimens of informis are at hand which have the hind wings 

 much shorter than the abdomen and the hemielytra reduced 

 as described above, while in typical marmorata the wings often 

 ■extend considerably beyond the abdominal apex and the hem- 

 ielytra are of course fully developed. But there are certain 



