446 



The Museum Gazette 



MALFORMATIONS OF THE BILL OF BIRDS. 



Mr. John Blackwall, F.L.S., in his " Researches in 

 Zoology," 1873) describes four instances of malformed bills, 

 in which the mandibles crossed each other in the manner 

 characteristic of the cross-bill. The first was a Jackdaw 

 killed at Bowers in the parish of Standon, Staffordshire, and 

 deposited in the Manchester Natural History Society's 

 Museum in 1830. The mandibles crossed each other "at 

 some distance from their points, the upper one curving 

 downwards on the right side of the lower one, which takes 

 an upward direction to the left." Though killed in severe 

 weather this bird was in excellent condition. 



The second was a Rook, also preserved in the Museum at 

 Manchester. The mandibles crossed but slightly near their 

 extremities. 



The third specimen was in the possession of Mr. R. Wood, 

 of Manchester, a well-known collector of natural history 

 specimens. In it the mandibles were greatly elongated and 

 much curved, as in the case of the Jackdaw. The upper 

 mandible crosses the lower one on the left side. In the 

 following case and the two preceding ones the upper crosses 

 the lower one on the right side. 



The fourth instance was a specimen of the Red-headed 

 Woodpecker of the United States. In this case the 

 mandibles "though pretty much elongated are but slightly 

 curved." 



No special examination would appear to have been made 

 to determine the cause of the malposition in these cases. We 

 may conjecture with great confidence that they were all 

 consequent on injury to one of the mandibles. The injury — 

 probably from shot — was most likely inflicted near to the base 

 of the mandible and had the effect of preventing growth at 

 the part involved ; under such conditions the uninjured side 

 would by its continued growth push the mandible over to 



