Vol. XI] COLE AXD LOVETT—LIST OF OREGOX DIPTERA 199 



low and more or less broken; distinct in the north, it is 

 merged into a complex mass in the south known as the 

 Klamath Mountains, a joining of the Cascade, Sierra 

 Nevada and Coast ranges. Toward the south, the general 

 elevation west of the Cascades increases. 



Forest Grove is about 28 miles west of Portland in a 

 region of rolling hills which are heavily wooded to the north 

 and south. There is a good deal of level farmland with 

 occasional patches of woodland or swamp. The annual 

 rainfall is about 45 inches, the wet season coming in the 

 winter and spring. Corvallis is about 65 miles south of 

 Forest Grove, in what is known as the Willamette valley 

 region. Many of our records are from Mary's Peak, a 

 mountain in the Coast Range of about 4,000 feet elevation, 

 lying some 15 miles south of Corvallis. 



The seacoast is largely a series of sand-beaches inter- 

 rupted by rocky headlands, and is a region of rather heavy 

 rainfall. The summers are cool, and a heavy growth of 

 grass and ferns spreads over the sand ridges. Several miles 

 north of Tillamook, these ridges inclose a number of lakes. 

 The last geological movement of the coast region here was 

 one of subsidence, the sea advancing over the land and 

 drowning the rivers in the lower portion of their channels. 



The Hood River Valley is a great sloping lava plain 

 from the foot of Mt. Hood to the Columbia River; through 

 this old plain the Hood River has cut a deep channel. Most 

 of the land is very fertile and the uncleared sections are well 

 forested. The section known as Dee is in the middle valley, 

 much higher than the level of the Columbia. Parkdale is 

 almost at the foot of Mt. Hood and has an elevation of 

 about 3,000 feet. Over the eastern rim of hills lies the 

 Mosier Valley, a different type of country. In these few 

 miles the rainfall drops from 30 to about 12 inches, and 

 crossing the next range of hills, we come to the Dalles, at 

 the edge of a great, wind-swept, arid region. 



The picturesque region around Mt. Jefferson has fur- 

 nished many interesting records in the diptera. Mt. Jeffer- 

 son rises rather abruptly from the rim of Lake Pamelia, 

 which has an altitude of 3,800 feet, and towers majestically 

 above the timber line to the zone of gnarled and twisted 



