and Classification of Birds. 261 



It may be worth while, here, to bestow a few remarks on 

 the developement or absence of the coeca coli, considered as 

 a zoological character. That their presence is of trivial or 

 no importance in the animal economy, when very small, is 

 proved by the occasional absence of these appendages, in 

 species which normally possess them : thus, of two young 

 male ospreys which I have recently dissected, they existed in 

 one specimen and not in the other. Again, Mr. Owen has 

 detected caeca, larger than in a lark, in a single individual of 

 the green woodpecker, throughout which group they are in- 

 disputably normally absent. The same anatomist has record- 

 ed their absence in a spoonbill, in which species I have found 

 them, though exceedingly minute, as in the storks. Analo- 

 gous discrepancies, however, obtain in various other organs, 

 serving to indicate the extreme caution requisite in deducing 

 conclusions from the examination of an insufficient number 

 of specimens. Of three giraffes, dissected by Mr. Owen, the 

 first possessed a capacious gall-bladder, whilst not the slight- 

 est trace of this organ existed in either of the others ; yet the 

 gall-bladder, (so far as has been observed), is constantly pre- 

 sent in the antelopes, and absent in the deer ; constituting, 

 in these groups, a distinctive character. A receptacle for the 

 secretion of the liver is also inconstantly present in some spe- 

 cies of birds ; the French Academicians failed to detect it in 

 four out of six demoiselles, [Gruidce : Anthropoides virgo) ; 

 yet in the parrots and pigeons, (both exclusively vegetable 

 feeders), its absence is an invariable characteristic; as its pre- 

 sence is throughout the group of Accipitres. The spoonbill, 

 like the storks and adjutants, is described to be destitute of 

 any muscles to the trachea, which ordinarily undergoes a con- 

 volution resembling the figure of 8 ; yet in a female which I 

 not long ago dissected, the windpipe proceeded straight to 

 the divarication of the bronchi, and it was furnished with a 

 small pair of sterno-tracheales. Of seven Bewick's swans, 

 which I have examined carefully, three possessed eighteen 

 tail-feathers, two nineteen, and the others twenty ; while a 

 number of hooper swans respectively presented twenty, twen- 

 ty-one, and twenty-two ; and however extraordinary the un- 

 even numbers may appear, yet, that no accidental deficiency 

 existed, was ascertained to complete satisfaction, by scrupu- 

 lous internal examination. It should be remembered that 

 much importance has been attached to this last character by 

 the discriminators of species ; and although it is true that 

 some species of motmots appear to nave constantly ten tail- 

 feathers and others twelve, (the outermost minute), yet, taking 

 the Tnsessores generally, I must still contend that the number 



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