EXTEBNAli ANATOMY. BILL. 
71 
culmen, or ridge of the upper^ is perfectly straight. The 
same also may be said of several of the long-billed waders, 
which at present form part of the genus Tetanus, so 
that it is in tlie Avocets alone {Jig. 3f). a.) we have this 
form at its maximum : here both the mandibles towards 
their extremity make a sudden curve upwards, and 
although very thin and delicate at this part, they are 
considerably compressed. The recurved-bill humming 
birds, of which there now appears more than one species, 
possess the same structure, with this exception only, 
that the gonysis somewhat 
thickened. For several years 
after we had published a 
figure and description of 
the Trnchilus recurviros- 
tris (Jig. 36. h.), the French 
ornithologists, with their 
usual hastiness of decision, 
maintained that tlic upward direction of the bill merely 
originated in that part having been artificially distorted 
in the only specimen then existing of the species. We 
did not think it worth while to combat this assertion, 
fuUy persuaded that, as soon as these gentlemen could 
receive ocular demonstration by an inspection of a se- 
cond example, they would change their opinion; and 
tliey have accordingly done so. Several specimens within 
the last few years have reached Paris, and it now appears 
that more than one species has the bill decidedly re- 
curved. Nothing is positively known of those peculiar 
habits which require a bill shaped so differently from all 
other birds. Wilson, in speaking of the American 
Avocet (liecnrinrosira Americana), merely observes, 
that it “ frequents the shallow pools of water in the salt 
marshes, wading about, often to the belly, in search of 
food; viz. marine worms, snails and various insects 
(crabs ? ) that abound among the soft muddy bottoms of 
the pools." 
( 67 .) VI. Truncated bills are, perhaps, the most 
singular of all the forms which nature has given to this 
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