142 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



those commou to Canada and Colorado and the Ohio Valley was only 

 found north of that divide {Q^cophora boreasella); the other species 

 appear to be generally distributed. 



It thus appears that while several species found in Colorado have here- 

 tofore been found only in Texas, and others have been found in Texas 

 and the Ohio Valley, or in the latter only, four Colorado species have 

 been found in Canada ; and these four have also been found in the Ohio 

 Valley ; and none of the described species appear to pertain to Colo- 

 rado and Canada alone. This appears somewhat anomalous, the more 

 especially as the flora and the birds of Colorado generally are supposed 

 to show northern rather than southern affinities. But it may be ex- 

 plained partly at least by the following considerations : — 



1. Tha number of known Texan species is at least four to one greater 

 than those of Canada, and the proportion of species from the Ohio Val- 

 ley is even greater still. Therefore it was to be expected that a larger 

 proportion of these would be found in Colorado than of the compara- 

 tively little known northern species. 



2. The greater number of Coloradan species are from the plains and 

 foot-hills south of the divide between the Platte and the Arkansas, say 

 below altitude 7,000 feet and latitude 39°, just as among birds, Geococcyx 

 californicmus, common in California, Arizona, New Mexico, Texas, and 

 the foot-hills of Colorado south of the " divide'", has never been found 

 north of it. But this consideration is not so weighty as it might seem 

 to be, because, since the distribution of the Tineina is so largely depend- 

 ent on that of the plants on which they feed, many species thus far 

 found only in the plains and foot-hills may be expected to be found at 

 still greater heights. 



3. The greater proportion of Texas species thus far made known are 

 from the region of Dallas — not of a very southern character. 



Still it remains a little strange that Colorado species from latitude 

 380 to 40°, and altitude 6,000 to 8,000, should seem to show greater 

 affinities with species from the Ohio and Mississippi Valleys and Texas, 

 latitude 34° to 40^, altitude 300 to 1,500 feet, than with species from 

 Canada and New England, at much higher altitudes and latitudes. 



Possibly further investigations may throw some light on it. But the 

 Tineina are not very numerous in species in Colorado, though some 

 species are very numerous in individuals; seventy-five species have 

 been described. I do not believe twenty-five more remain to be de- 

 scribed, and these will be found — or most of them — in the extreme 

 northern, southern, or eastern portions of the State. Additional dis- 

 coveries will generally extend the range in latitude, longitude, and alti- 

 tude of species already known, rather than make known new species. 

 Nevertheless, of the fifty-five species as yet only known to Colorado, 

 a large proportion may, and probably will, be found in Canada, and 

 thus it will result — as from other reasons might be anticipated — that 

 the Tineina of Colorado will show greater affinities with those of Canada 

 than with those of Texas. 



