light and so variable as not to be worth notice,
except that in two skeletons of the Penguin duck the terminal portion
of the scapula was much attenuated.

In the bones of the leg and wing no modification in shape could be
observed. But in Penguin and Hook-billed ducks, the terminal phalanges
of the wing are a little shortened. In the former, the femur and
metatarsus (but not the tibia) are considerably lengthened, relatively
to the same bones in the wild duck, and to the wing-bones in both
birds. This elongation of the leg-bones could be seen whilst the bird
was alive, and is no doubt connected with its peculiar upright manner
of walking. In a large Aylesbury duck, on the other hand, the tibia was
the only bone of the leg which relatively to the other bones was
slightly lengthened.

_On the effects of the increased and decreased Use of the Limbs._--In
all the breeds the bones of the wing (measured separately after having
been cleaned) relatively to those of the leg have become slightly
shortened, in comparison with the same bones in the wild duck, as may
be seen in the following table:--

+--------------------+-----------------+-------------------+-----------+
| | Length of Femur,| Length of Humerus,| |
| Name of Breed. | Tibia, and | Radius, and | |
| | Metatarsus | Metacarpus | Or as |
| | together. | together. | |
+--------------------+-----------------+-------------------+-----------+
| | Inches. | Inches. | |
|Wild mallard | 7.14 | 9.28 | 100 : 129 |
|Aylesbury | 8.64 | 10.43 | 100 : 120 |
|Tufted (Dutch) | 8.25 | 9.83 | 100 : 119 |
|Penguin | 7.12 | 8.78 | 100 : 123 |
|Call | 6.20 | 7.77 | 100 : 125 |
+--------------------+-----------------+-------------------+-----------+
| | Length of same | Length of all the | |
| | Bones. | Bones of Wing. | |
| +-----------------+-------------------+ |
| | Inches. | Inches. | |
|Wild duck