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IOWA ACADEMY OP SCIENCE Vol. XXIV, 1917 
the valley of the Saskatchewan and on the Bow river from Cal- 
gary where it is mixed with P. Engelmanni. It is found also on 
the coast of Maine, through northeastern Vermont and westward 
through northern Michigan and Minnesota to the Black Hills of 
Dakota, .where it is known as the Black Hill Spruce. In Mon- 
tana, along the Rocky mountains, it reaches its greatest develop- 
ment along streams and lakes in the Flathead region, at an ele- 
vation of 2,500 to 3,500 feet. 
Picea alba , to which this fossil wood is probably nearly re- 
lated, is characterized by thin summer wood, rather prominent, 
upwards of one-fourth the spring wood, from which the trans- 
ition is gradual, rarely abrupt; the structure rather dense and 
the tracheids squarish. The spring wood is open.; the tracheids 
are squarish-hexagonal, uniform in very regular row T s, and the 
walls thin. The resin canals are scattering, and the rays are 
not very numerous. The bordered pits are found in one row, 
are numerous, and are round or elliptical. The orifice is usually 
large. In the summer wood the pits become remote or obscure, 
and the orifice usually becomes a prolonged slit. In the fossil 
wood we find a number of these points present, especially in the 
shape of the tracheids, the open spring wood with its thin walls, 
which failed to withstand pressure. The tangential pitting of 
the fossil wood is better marked than that of Picea alba. These 
and other similarities give us sufficient grounds to place them 
in close relation to each other. 
Department of Botany, 
Grinnell College. 
