312 E. G. LINSLEY 



Taxodiaceae. However, Vandykea is isolated taxonomically and 

 apparently has southern rather than northern affinities, and I 

 have classed it as "-Calif ornian" (see below). 



In Oregon and California, the Sierra-Cascades (arid) phase of the 

 Vancouveran subfauna is quite distinct from the coastal (humid) 

 phase, although the two approach each other more closely in Wash- 

 ington and merge in British Columbia. In general, most Ceram- 

 bycidae that occur in the Sierra-Cascade Vancouveran are found 

 also in the coastal phase. Apparent exceptions include: Desmocerus 

 auripennis Chevrolat, Tetropium ahietis Fall, Oeme calif ornica 

 Linsley, Pachyta armata LeConte, Leptura obliterata soror LeConte, 

 Semanotus amethystinus LeConte, Clytus planifrons LeConte, C. 

 clitellarius Van Dyke, Neoclytus mibilus Linsley, and Leptostylus 

 nehulosus Horn. Species of the coastal Vancouveran not known to 

 occur in the Sierra-Cascade phase include: Evodinus vancouveri 

 Casey, Leptura obliterata obliterata LeConte, Desmocerus cribri- 

 pennis Horn, Callidium vandyke, C. sempervirens Linsley, Clytus 

 blaisdelli Van Dyke, and Plectrura spifiicauda Mannerheim. Mela- 

 nism is a marked characteristic of the humid Vancouveran and is 

 particularly pronounced in Piirpuricenus dimidiatiis Horn, Necyd- 

 alis laevicollis LeConte, and Judolia quadrillum LeConte. 



The Rocky Mountain area, lying between the Vancouveran and 

 Alleghenian endemic reservoirs, has few endemic cerambycid genera 

 of its own (e.g., Elatrotrypes, with ancient northern affinities), 

 and the intermountain or Great Basin area contains only one, 

 the monotypic Megascheuma, obviously derived from the austral 

 Megacyllene and adapted for life in the roots of shrubby compositae. 

 The present cerambycid fauna is made up primarily of Holarctic 

 elements of recent origin, with an intrusion of Vancouveran forms, 

 especially in the north and, to a lesser extent, of Sonoran elements 

 in the south. A few Alleghenian representatives are to be found on 

 the eastern slopes of the mountains, emphasizing a long separation 

 of Vancouveran and Alleghenian elements, and these are mostly 

 recent arrivals, many of which have followed up the river courses 

 from the Mississippi Valley, e.g., Neoclytus caprea Say. The Great 

 Plains area to the east, which apparently began to develop some of 

 its present characteristics in the Miocene, has produced the prionine 

 subgenus Homaesthesis, and this, like Megascheuma, exhibits 



