302 On a Nestling Calopsittacus novcs-hollandice.


hollow : while the inferior border of the jaw in the adult is

semicircular, in the nestling straight, until near the tip.


The fact that the external nostrils open at a point above

the angle of the gape in the adult, and much in advance of this in

the nestling, suggests considerable differences in the relative

rates of growth of the several parts of the jaws between the

nestling and adult stages. Observations on this point are

evidently much needed. As to the significance of these changes

nothing can profitably be said at this juncture. But it would

seem that the curious spoon-shaped tip of the upper jaw of the

nestling may represent a stage in the ancestral history, when the

jaws were used for softer food.



Fig. 2.



Fig. 3.


Fig. I. Head of a nestling Pscp/iotus multicolor showing

the peculiar relation of the lower to the upper jaw, and the

marked distinction between the premaxillary and maxillary

portions of the upper jaw. Note also the striking difference in

shape between the beak of the nestling and that of the adult.


Fig. 2. Head of an adult male Psephotus multicolor to

show the marked difference in the form of the beak between

nestling and adult.


Fig. 3. Head of a nestling Calopsittacus ?iov<z-hollaudics

one day old, showing the great size of the premaxillary portion



