42 
PICUS TRIDACTYLUS. 
whence Vieillot took his highly characteristic name, 
( Picus hirsutus , Pic a pieds vetus ,) the feathered tarsi, 
a peculiarity which this alone possesses to the same 
extent. The plumage is an uniform black above in the 
adult, with the top of the head yellow in the male, 
while the southern, whose tarsi are naked, is black 
undulated with white, the male having the sinciput red. 
It is worthy of remark, that the three-toed group found 
in arctic and in tropical America, should have no 
representative in the intermediate countries. 
Although these are the only three-toed woodpeckers 
noted as such in the hooks, several others are known 
to exist, some of which, long since discovered, have 
through inadvertence, or want of proper discrimination, 
been placed among the four-toed species. The three- 
toed woodpeckers have been formed into a separate 
genus, a distinction to which they might indeed be 
considered entitled, if they all possessed the other 
characters of the present ; but, besides that this character 
appears to be insulated, and of secondary importance, 
(since all forms of the bill known among the four-toed 
species are met with among the three-toed, which ought, 
therefore, to make as many groups as there are forms, 
instead of a single one,) the naturalist is perplexed by 
the anomalous species that inhabit India, of which one 
has only a stump destitute of nail, and another merely 
a very small nail without the toe, and, as if nature took 
delight in such slow and gradual transitions, two others 
furnished with both toe and nail, have the toe exceedingly 
short, and the nail extremely small! This serves to 
demonstrate that Picus , like other natural groups, admits 
of subdivision. These, however, ought not to be 
separations ; and the genus has been left comparatively 
untouched by the great innovators of our day, who have 
only established three genera from it. The first of these, 
Colaptes , of w hich P. auratus of North America may be 
considered the type, comprises the species that have 
four toes, and slightly curved bills, forming the passage 
to Cuculus; another, for which the name of Picus is 
retained, includes the four-toed species with straight 
