40 PROCEEDINGS OF THE NATIONAL MUSEUM vol.84 



eiices in these structures cannot be used for specific segregation. In 

 this study only the larger punctures of the elytra have been found 

 to be of value, and their constancy appears to be sufficient to justify 

 their use. 



Chiefly owing to the exclusive use of color as a distinguishing 

 character, several of the common American species have been com- 

 pietel}^ confused under two or three names. The supposed recogni- 

 tion of the European chrysoinelinus from this country only served 

 to increase the difficulty. Under the name jocosus and chrysoinelinus 

 have been included indiscriminately at least three common species, 

 as is demonstrated by the fact that the Horn collection contains all 

 three of these species under each name. The names macuUcolUs of 

 LeConte and acaudus of Say have in the past been suppressed on 

 the basis of color similarities. 



Because of the loss of the Say types, it is impossible to be sure 

 of his species. His descriptions, in combination with the type lo- 

 calities, seem to be sufficient to distinguish both jocosus and acaudus. 



No specimen from America has been seen that can be placed with 

 European specimens of clirysomelinus. This species runs in our key 

 to r-ulomiLs but differs especially from that species by the absence 

 of the extra discal puncture near the humerus of the elytra. 



Because of this confusion and the incorrect statements in Horn's 

 descriptions and synonymy of jocosus and chrysomelinus^ it is im- 

 possible to use any of the records published for these species. It 

 cannot be determined, except from the specimens, to which of the 

 valid species they belong. This is also true to a large extent of 

 scitulus^ nanus, califomieus, and elcgans. 



Certain of the characters used in the key need explanation. The 

 large setiferous punctures of the elytra are arranged in a regular 

 pattern, which holds throughout the genus and consists of a series 

 of one to four punctures along the suture, a series of three to five 

 along the lateral margin, a series of one to three along the apical 

 margin, and five or six punctures forming an oblique quadrilateral 

 on the disk. Any of these punctures may disappear in certain 

 species, but the basal members of the sutural and lateral series are 

 more permanent than the apical members. The sutural series is said 

 to be present if one puncture of this series remains on each elytron. 

 The "median discal puncture" is situated at basal third at the middle 

 of the disk. The maculation of the pronotum is sometimes very 

 faint and diffuse, but the immaculate forms are never darker at the 

 center of the disk. The folding of the hind wings beneath the 

 elytra frequently forms a small triangular black spot at the scutel- 

 lum, which is visible through the elytra. This is not considered to 

 invalidate the statement "elytra without large scutellar black spot." 



