1919] Distribution of Insects 11 



northern species extended much farther south than at present 

 and in general were more in evidence in the south than now, 

 but within recent times they have undoubtedly both retreated 

 and decreased in numbers in the southern areas. The southern 

 forms have, on, the contrary, been doing the opposite so that 

 they have gradually supplanted the preceding. This, therefore, 

 accounts for the fact that there are islands of northern forms 

 within the territory occupied by southern forms. Wherever 

 southern forms have run north, they are always to be found 

 connected with their basic stock in the south, no matter how 

 far north they have gone and no matter at what time they 

 advanced. Some of the characteristic species of the Californian 

 fauna are the members of the dilatatus group of Anisodactylus 

 in the Carabidce; Dystaxia, Schizopus and Glyptoscelimorpha, 

 in the Btcprestidce; Ipochus fasciatus Lee. in the CerambycidcE; 

 Phloeodes, Coelus, Eulabis, Nycotporis, Cibdelis and Coniotis, in 

 Tenebrionidce; and Trigonscuta and Rhigopsis in the OtiorychincB. 

 Our west coast fauna we thus find has the bulk of its species 

 of insects included within the very old Vancouveran fauna and 

 the equally old Californian fauna, two faunas that are restricted 

 to the Pacific Coast and that have passed through the Pleisto- 

 cene without much injury to themselves. Supplementing these, 

 are the several marginal faunas of the mountains and the 

 desert faunas of the southeast. The Vancouveran, like those 

 found in the mountains of western Idaho, and in the southern 

 Alleghanies, is a relict fauna, a remnant of a more or less upland 

 fauna which was widely distributed throughout the more 

 northern parts of North America during Tertiary times. It is 

 the largest remnant of the three and is only surpassed among 

 similar fauna by that of the Japano-Manchurian region. The 

 Californian is quite isolated though it shows a strong relation- 

 ship to that found in the more barren parts of northern Chili 

 and Peru. The marginal faunas on our mountains link up our 

 territory with that to the north and northeast of us and the 

 Sonoran does the same with regard to the country to the south- 

 east. Certain of our peculiarities can also be indicated by 

 considering the subject from a negative standpoint. For 

 instance, we find that very little of the Neotropical or tropical 

 fauna of South America, has reached us, whereas quite a 

 noticeable amount has found its way into eastern North 

 America. Diabrotica soror Lee. is one of our few derivatives 



