SUMMARY

1. The silky flycatchers, waxwings, and palm-chats are included in the family Bombycillidae; the Ptilogonatidae and Dulidae are reduced to subfamily rank.

2. The coloration of the birds of each subfamily is different because the ecological needs are different.

3. Waxwings were at one time regularly migratory, but are now nomadic, since they are adapted to live in northern lat.i.tudes for the entire year.

4. The corresponding bones in different members of the family closely resemble one another, and the differences which do exist are the results of responses within relatively recent times to changes in habits.

5. In the Bombycillidae a rounded wing is judged to be the primitive condition. As the wing becomes more pointed, the humerus becomes shorter and its external condyle longer.

6. The hind limbs are short in birds that depend most on flight power, but are longer and the distal elements are disproportionately longer in birds that depend on saltation or on running.

7. The pygostyle varies in shape and size between genera and even between some species.

8. The pectoral muscles differ in size only slightly in the different members of the family, but the insertions are more extensive for these muscles in birds that fly a great deal.

9. The muscles of the hind limb vary in ma.s.s, but not in kind, in the members of the family Bombycillidae.

10. In the Bombycillidae that depend on flight power, rather than on saltation or on running power, there is a tendency for the digestive tract to become shorter and for the whole visceral ma.s.s to become more compact.

BIBLIOGRAPHY

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