74 
REMARKS ON THE BITTERNS. 
tion of it in certain Ibises. All have an amazing spread of wing in proportion 
to the weight of their bodies; but the skeleton is extremely light and frail, more 
especially in the three, or in the ultimatum degree in the two, first divisions. 
The sternum is short, and singly emarginated behind; and the furcula is attached 
to the anterior portion of its ridge or keel. The Ibises, however, and to a less 
extent the Spoonbills, form exceptions to this, in so far as the breast-bone is 
doubly emarginated at its posterior edge, and the Ibises otherwise approximate 
in their conformation to the Curlews and others of that group, with which 
Cuvier associated them, having been induced to do so, probably, from the near 
resemblance which is observable in the skeleton; still we require only to know 
the digestive organs, and mode of propagation, of the Ibis group, to assign 
immediately its true position in the system. The character of its plumage, again, 
at once indicates its affinity to the Stork rather than to the Curlew: and to 
mention still another distinction, it may be observed, that all the species brought 
together under my term Robustirostres have the hind claw produced, and articulated 
on an even plane with those in front, whereas the Scolopacidce on the one hand, 
and the Gruidce (or Cranes) on theother, have the hind-claw elevated upon the 
tarsus. Moreover, the weight of a Curlew is very nearly double that of an Ibis 
of the same dimensions : even their attitude, and carriage, sufficiently indicate 
the very distinct divisions to which they respectively appertain. A peculiar and 
constant character of the Ardeidce (as here limited) is the tuft of unelastic 
cottony down upon the breast, and again to the interior of the thigh. This 
causes a singular glandular structure which secretes a powdery matter resis¬ 
tive of moisture, much of which (powder) is retained, as in a powder- 
ball, by the down specified. After handling and rubbing the fingers in this 
down, they may be dipped into water without being wetted. The powdery 
substance is distributed over the plumage by merely shaking it, and of course 
tends to keep that portion of it dry which would otherwise be almost in a 
soaking condition. The site of its production, moreover, is so ordained as to 
protect the muscle of the breast from being chilled by contact with water; for 
a Heron will often strike a fish at so great a distance, that the body inclining 
forward upon the pivot of the legs, dips the breast when the bird has stood, as 
it often does, in water reaching to the commencement of the bare part of its 
tibiae ; the impervious down thus appearing as a very beautiful provision of 
Nature. I was led by actual observation to appreciate this use of it, but still 
am by no means satisfied that I yet comprehend the final purport of this 
peculiar structure, for the Bitterns, which are not habitually piscivorous, possess 
it equally with the most piscivorous Herons. 
All the members of this family seize, and in many instances transfix, their 
prey by an instantaneous stroke, which the great length of the neck enables 
