OF ARTS AND SCIENCES. 45 



Nuthatches {Sitta canadensis^. At the lower elevations, 

 groves of White Ppine occur, usually below 800 feet, though 

 scattering trees are to be found, often of great size, up to 2,500 

 feet or slightly less. These pine groves are carpeted with 

 needles, which make a dry and often rather barren floor. Here 

 we find such sub-Canadian species as Slate-colored Juncos 

 {Junco hyemalis) , Myrtle Warblers {Dendroica coronata) , Black- 

 burnian Warblers {^Dendi'oicablackbicrni(2^ 2in^^Q.rm\\.'T:\Lx^xs)l- 

 es {Hylocichla guttata pallasii^ . A number of these sub-Cana- 

 dian species are rather sharply limited in their breeding range 

 by the upper Canadian zone, and occur only rarely on its lower 

 edge. Such are the Yellows-bellied Sapsucker, Olive-sided 

 Flycatcher, Blue-headed Vireo, Black-throated Blue Warbler, 

 Magnolia Warbler. Bay-breasted Warbler, Blackburnian War- 

 bler, and Oven-bird. In a general w^ay, the 3,000 foot contour 

 marks the lower edge of the upper Canadian zone on the 

 higher mountains where the slope exposure is to the south. 

 On northern, shaded slopes, this limit is some 500 to 1,000 feet 

 lower, and on both north and south slopes the cold mountain 

 streams serve to carry down with them strips of the upper 

 Canadian as narrow tongues into the lower woods. In a region 

 still covered b}' primeval forest, the upper Canadian area is no- 

 ticeably lower on the mountains than on territory which has 

 once been stripped of its heavy growth. Thus in the undefiled 

 forests of the upper Pemigewasset, Canadian Spruce Grouse 

 {Canachites canadensis canace) occur along the stream at least 

 down to 2,000 feet, though on the mountains which have been 

 burned or lumbered, only deciduous or mixed growth is found 

 at this level, quite unsuitable for high northern species. An 

 interesting observation I have several times made among the 

 damper, higher woods of the sub-Canadian area on the White 

 Mountains, is that the Lad3'-'s Slipper {^Cypidpediiini acanle) 

 growing from 1,800 to 2,500 feet or so, is prevailingly white in- 

 stead of pink. In late June, 1900, almost three fourths of the 

 numerous blossoms seen on the Carter Notch and Nineteen-mile 

 Brook trails, were snow white or barely flushed with pink above 

 1,800 feet, and again in mid-June, 1902, along the same trail, 



