MONOGRAPH OF THE GENUS SAPERDA 5 



cleared up by the characterization of h o r n i i . Our study has 

 brought out the interesting fact that, among the so called western 

 forms of m o e s t a , one is identical with the European p o p u 1 n e a, 

 and can not be differentiated in any particular from that species. We 

 find that two species have been included under the name t r i d e n - 

 t a t a , as well as a distinct variety of lateralis. All but three 

 American species occur in New York State, and our study has on 

 that account been monographic. 



Series of all American species have been examined, and several 

 characters not noted or seen by former students have been found. 

 The European and Asiatic species have all been studied, except a 

 few Siberian forms which are probably only varieties. Since both 

 sexes were not obtainable of all the exotic forms, it has not been 

 possible to include a discussion of them in this paper. They are 

 mentioned wherever it is necessary to show the close relationship 

 existing between the two faimas.^ The 13 species and one variety 

 listed by Samuel Henshaw in 1885 have been increased by us to 15 

 species and five subspecies or varieties. 



The species are so closely related, though differing greatly from 

 each other in several characters, that subdivision of the genus is not 

 considered advisable and would not be practicable, as whatever char- 

 acters might be used, disappear so gradually that the species could 

 not be as well arranged as in the present grouping, and it would tend 

 to bring widely separated forms close together. 



The exotic species have been divided into a number of genera and 

 subgenera on characters which we consider, from our studies of the 

 entire group, degrees of specialization. 



Mr Mulsant divided the European species on the relative size of 

 the metathoracic episterna, the form of elytra and on the antennae 



Tn studying the two faunas together, the indications are very strong 

 that they were derived from common ancestors; and, while the two are 

 quite distinct in many ways, they have evidently specialized along different 

 but parallel lines, and their characters are intermediate. 



The fact that the American species are all of eastern origin (except 

 those few that show their immigration into the Pacific fauna through 

 Alaska) and the Old World ones of western origin would tend to show 

 that at some remote epoch there was a connection between the two 

 continents. 



