PEELIMINAEY CLASSIFICATIOISr OF SCOLYTOIDEA. 211 



Family PLATYPODID^. 



The family Platypodidse has a wide range through the temperate, 

 subtropical, and tropical regions of both continents. 



There are many features in the distribution of genera and species 

 which are of special interest, but there is need of information on many 

 species from the different countries which at present are poorly or 

 not at all represented in collections. 



PAIRED SPECIES. 



The subject of so-called paired or parallel species is of special 

 interest in connection with a study of the distribution. There are 

 some striking examples of paired species in the genus Dendroctonus 

 which, if they occupied the same local faunal area, would be difficult 

 of separation on account of their close resemblance in structural 

 characters. These paired species are hrevicomnis and harberi, frontalis 

 and arizonicus, mexicanus and parallelocolUs , monticolse and ponde- 

 rosse, piceaperda and engelmanni, punctatus and micans, and terebrans 

 and valens. In each case the pairs are more or less widely separated 

 from each other in their geographical distribution, as, for example, 

 Tnicans of northern Europe and punctatus of the Appalachians of 

 North America, frontalis of the Southern States and arizonicus of 

 Arizona, harieri of Arizona and New Mexico and irevicomis of the 

 Pacific Slope States, Idaho, Montana, and part of Wyoming, ponde- 

 rosse of the central and southern Rocky Mountains and monticolse in 

 the Northern Rocky Mountains and Pacific Slope. 



There are any number of similar cases of so-called paired species 

 in other genera, and the supposition that some of them are one and 

 the same species has led to considerable confusion concerning the 

 true range of a species. Between North America and Europe we 

 have several examples, such as Anisandrus pyri of America and 

 Anisandrus dispar of Europe, Dryocoetes autograplius of Europe and 

 Dryocodes septentrionis of the western coast and Alaska of America, 

 Xyloterus lineatus of Europe and Xyloterus hivittatus of America, 

 Hylurgops glahratus of Europe and Hylurgops pinifex of America. 

 There are many others common to two or more countries which super- 

 ficially seem to be the same. 



REVIEW OF TAXONOMIC CHARACTERS AND CHARACTERISTICS. 



In a review of the foregoing discussion of the morphological char- 

 acters to be found in the different stages of the scolytoid beetles and 

 of the physiological characteristics in their habits, it is shown that 

 there is a wide range of taxonomic elements by which to distinguish 

 species and genera and to indicate or fix their position in the classifica- 

 tion. Indeed the vast number of these characters and characteristics 



