216 On the Natural History of 
of cats-tail; nor is the epithet inappropriate, for their long hanging 
tails, no less than their mode of climbing the branches, gives them 
some distant resemblance to that quadruped. I have no doubt that 
the great length of tail possessed by nearly all the cuckoos is given 
to them as a sort of balance, just as a rope-dancer, with such an instru- 
ment in his hands, preserves his footing when otherwise he would 
assuredly fall. Remote, therefore, as the cuckoos unquestionably are 
from the typical Scansores, we yet find the functions of the tail con- 
tributing to that office, although in a very different mode to that which 
it performs among the woodpeckers, the parrots, and the creepers. 
The structure of the feet, as before observed, is the only circum- 
stance which would lead an ornithologist to place these birds among the 
climbers, supposing he was entirely unacquainted with their natural 
history, properly so called, or with their close affinity to the more 
perfect Scansores. The toes, indeed, are placed in pairs ; that is, 
two directed forward, and two apparently backward, but a closer in- 
spection will show that the latter are not strictly posterior, and that 
they differ so very materially from those of the Picidce, (the pre- 
eminently typical family of the climbers,) as clearly to indi- 
cate a different use. The organization of the external posterior toe 
of all the woodpeckers, parrots, and toucans, renders it incapable of 
being brought forward, even in the slightest degree ; whereas, in 
the cuckoos this toe can be made to form a right angle with that 
which is next it in front, from which circumstance it has been term- 
ed versatile : this term, however, is not strictly correct, inasmuch 
as the toe cannot be brought more than half way forward, although 
it can be placed entirely backward. Now this form, which is ob- 
viously the least developed state of the scansorial structure, accords 
exactly with the rank of -the family, which is that of the most aber- 
rant group in the circle, and furthest removed from the type. The 
cuckoos, in fact, are half-perching, half-climbing birds, not only in 
their feet, but, as we have seen, in their manners. No one, from 
seeing them alive, would suppose they were truly scansorial birds : 
and yet it is highly probable that this singular power of varying 
the position of one of their toes, gives them that quickness of mo- 
tion, and firmness of holding, which accompanies the v habits just 
mentioned. 
There is another circumstance in the history of this family of 
birds which, with one solitary exception,* is altogether peculiar, as 
they contain the only parasitic birds yet known. This term, indeed, 
has been applied, I think improperly, to other genera, which, 
* Molothrus pecoris, see North. Zool- (the cow-bunting) of North America. 
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