II.
EXPLANATION OF TERMS USED IN DESCRIBING THE EXTERNAL FORM OF BIRDS.

½ NAT. SIZE.

Turdus migratorius, L.

REFERENCES TO THE FIGURE.

N. B. In the figure the adjacent regions are separated by a double bar, with the letters belonging to each affixed.

Note.—I am under obligations to Professor Sundevall of Stockholm and Dr. Sclater of London for assistance in correcting and improving the present article.—S. F. Baird.

B. Head.