on the Nestling of Fraser's Touracou. 61


Briefly, the two nestlings superficially bear a very close

resemblance one to another : but this fact must be put down

rather to convergence than to any very close relationship.


Both are alike downy, but whereas the young Touracou is

clothed only in nestling down known as pre-pennse, the young

Hoatzin has, in addition, an extra covering of down feathers—

the pre-plumulse.


Both in the Touracou and the Hoatzin the feet are of

enormous size, but in the latter all the front toes are turned

forward.


It is in the wing that the most striking features occur, both

in the young Touracou and the young Hoatzin. The form of

this organ in the Touracou can be seen in the plate accompany¬

ing this paper. The wing at this stage {fig- 4)—one month old—

resembles that of the young Hoatzin (ftgsi-f) of the same age : and

partly on this account and partly on other grounds, I am inclined

to believe that, when we come to know more of the earlier history

of the young Touracou, we shall find a similar series of the

same remarkable phases of development.


These we may briefly outline as follows : At hatching the

wing of the young Hoatzin is remarkable for the great length of

the hand, which is considerably longer than the forearm, and

armed with two strong claws, one on the thumb, the other on the

index finger. The quill feathers are represented only by

rounded brush-like tufts of feathers.


The considerable length of the hand at this stage would

probably never have excited more than passing comment, whilst

the claws would have been regarded as vestiges of a reptilian

stage ; had it not been for the discovery of Mr. C. Quelch, who

in the Ibis of 1890 published a most interesting and remarkable

account of the life-history of this bird.


He showed, beyond cavil, that the young are quite unlike

birds hatched in an arboreal nursery generally, inasmuch as

they leave the nest in a few hours and climb about the tree in

which it is placed. In other words the young are precocious.

In the climbing not only the toes and feet are used, but the wing

also. Hence the great length of the hand, and the size of the

claws (see fig. 1 on the plate.). As development proceeds the



