ON 
A REMARKABLE FORMATION OF THE BILL 
OBSERVED IN SEVERAL SPECIES OF BIRDS. 
—~—-— 
Instances of extraordinary deviation from typical 
forms in the structure of animated beings are highly 
interesting to the physiologist, whether his attention 
be directed to the influence which organic modifica- 
tions exercise upon the animal economy, or to the 
more abstruse investigation of the predisposing 
causes of these curious phenomena. Such being the 
case, a concise account of a few examples of this 
nature, which have come to my knowledge, will, it is 
presumed, require no apology. 
A Jackdaw, killed at Bowers, in the parish of 
Standon, Staffordshire, was presented, in January 
1830, to the Society for the Promotion of Natural 
History, established in Manchester, and is deposited 
in their Museum. This bird, in the structure of its 
bill, presents a form closely resembling that which 
so strikingly characterizes the species constituting 
the genus Loaia, the mandibles crossing each other 
at some distance from their points, the upper one 
