320 NORTHERN THREE-TOED WOODPECKER. 
This species is eminently distinguished among the North 
American and European woodpeckers by having only three 
toes, the inner hind toe being wanting ; besides which it has 
other striking peculiarities, its bill being remarkably broad 
and flattened, and its tarsi covered with feathers half their 
length; the tongue is, moreover, not cylindrical, but flat and 
serrated at the point, which conformation we have, however, 
observed in the three European spotted woodpeckers, and in 
the American Picus varius, villosus, pubescens, and querulus. 
In ail these species the tongue is flat, with the margins pro- 
jecting each side, and serrated backwards, plain above, convex 
beneath, and acute at the tip.* 
- Linné, Brisson, and other anterior writers, confounded this 
northern bird with a tropical species, the southern three- 
toed woodpecker, Picus undulatus of Vieillot, which inhabits 
Guiana, and, though very rarely, Central America, but never so 
far north as the United States. It is the southern species of 
which Brisson has given us the description, while Linné de- 
scribed the present. It is nevertheless probable that he had 
the other in view when he observes, that in European speci- 
mens the crown was yellow, and in the American red, though, 
as he states, from Hudson’s Bay. The latter mistake was cor- 
rected by Latham, who, however, continued to consider the 
* Mr Swainson has thought the three-toed woodpeckers of sufficient 
importance to form a subgenus ; and I rather think that he will be 
right in his views. These birds were included by Koch in his genus 
Dendrocopus, of which they possess the general form and colour, but 
differ chiefly in the structure of the foot. I believe more species will 
be discovered in the south parts of America ; and Mr Swainson, although 
he does not enter minutely into the distinctions, considers that there 
are two confounded under the northern three-toed woodpecker. The 
present bird he denominates Apternus Arcticus, and retains tridactylus 
for the three-toed woodpecker of Pennant and Edwards, the Picus 
tridactylus of Forster. The chief differences are in the greater size of 
the former, the difference of marking, and the relative proportion of 
the wings. The Northern Expedition observed the first only on the 
eastern declivities of the Rocky Mountains, where the common species 
was also procured. This investigation may be worth the while of those 
persons who have the opportunity.—Ep., 


