214 On the Natural History of 



necessary data for testing the soundness of the results there given, 

 that I propose, in this publication, to treat of such groups more at 

 large, rather wishing to lay before the experienced ornithologist the 

 reasons upon which my opinions are grounded, than to have it sup- 

 posed I wish those opinions to be received upon trust, without the 

 production and evidence of facts. 



I believe there cannot be the slightest doubt that the family of the 

 Cuculidce or Cuckoos, is the most aberrant family of the scanso- 

 rial tribe. This conclusion may be arrived at by two ways, first, 

 by considering the natural habits and structure of the birds them- 

 selves ; and secondly, by ascertaining the relations of affinity which 

 they bear to other groups, wherein the scansorial power is more de- 

 veloped. The first line of inquiry should always take precedence 

 of the second ; because, without understanding the history and 

 structure of a bird, it is impossible to associate it with its natural 

 companions. A rapid survey, therefore, of the chief peculiarities of 

 the group before us, may precede a more minute inquiry into its 

 contents. 



The Cuckoos are altogether natives of such climates as lie beyond 

 the influence of frost, and their number seems to be regulated by 

 the proximity of their native country to the equator. Thus the 

 ornithology of Europe presents us with only two species, both of 

 which, during the summer, take up a temporary residence in lati- 

 tudes otherwise cold, but which they hastily quit at the approach 

 of autumn ; and so congenial is warmth to their nature, that even 

 the mild temperature of an Italian winter is not sufficient to retard 

 their return to the sultry groves of Northern Africa. There is a 

 fact regarding their structure, which appears connected with this 

 susceptibility of cold, and which I believe has not hitherto been no- 

 ticed. All the Cuckoos, both of the old and the new world, which 

 I have had the opportunity of dissecting, are remarkable for the 

 thinness and delicacy of their skins, so much so, indeed, as to render 

 their preservation in an entire state, extremely difficult to inexpe- 

 rienced hands. Every one who has skinned the common British 

 species must doubtless have observed this. On the other hand, as 

 if to compensate for this delicacy of the cuticle, the feathers, more 

 especially upon the back and rump, are unusually thick set and 

 compact. Nor is this peculiarity of organization confined to the 

 family before us, for we find La Vaillant observing the very same 

 thing in respect to the Ceblepyrina? of Africa, and nearly the whole 

 family of pigeons have very thin skins, and thick set feathers. Nor 

 are these relations of analogy without method, for on comparing 

 the circles in which the Cuculida;, the Ceblepyrince, and the Coliim- 



