SYRINX OF PENGUINS. 15 
however, have a somewhat greater circumference ; and this is specially noticeable in 
the last. But the bronchial semi-rings 2-4 have a very wide span, so that the windpipe 
in this region reaches its greatest dorso-ventral width; from the fourth bronchial 
semi-ring backwards the circumference of the bronchus decreases rapidly. Only the 
first bronchial ring is complete—to its inner rim is attached the upper end of the 
membrana tympaniformis. The intrinsic muscles terminate in the middle of the ante- 
penultimate ring, while the extrinsic muscle leaves the trachea at about the twentieth 
ring from the syrinx, counting from the last tracheal ring forwards. The trachea of this 
species shares with that of the remaining penguins the peculiarity of a median septum 
which extends the whole length of the trachea, from the syrinx forwards as far as the 
upper third of the tracheal tube. This 
septum is made up, in the adult, of a 
number of bony bars corresponding 
numerically to the number of the tracheal 
rings (Fig. 5); while that of the nestling 
differs from that of the adult only in 
being, like the rest of the trachea, entirely 
cartilaginous. 
VI.—Some Facts ConcERNING THE 
EMBRYO AND NESTLINGS. 
I propose to deal here with a few facts 
concerning the rhamphotheca and the ex- 
ternal nares, the palate, the developing 
wine and the tarso-metatarsus. FIG, 5,—THE SYRINX OF AN ADULT EMPEROR PENGUIN, SIDE 
ad VIEW, AND IN SECTION TO SHOW THE TRACHEAL SEPTUM. 
B = bronchidesimus; br. = bronchus; s. = septum; 
tr. = trachea; t. = trachealis muscle; tm. = tympanic 
The Eehamphotheca. ae 
“ I. = 1st tracheal ring; I.1 = 1st bronchial ring; 
The shape of the beak in the embryo ii. ond bronkbial ice, 
Emperor Penguin, at the time when the ' 
feather papille are just making their appearance, differs from that of the nestling, just 
as markedly as the beak of the latter differs from that of the adult. 
In the embryo at the age just indicated the beak is relatively long, cylindrical, 
slightly swollen at the tip, and shows no trace of the egg-tooth. The anterior nares are 
open, but there is no sign of separate rhamphothecal plates, or of the groove which later 
appears in front of the nostrils. 
In the newly-hatched nestling the culmen of the beak is arched, while near the tip 
is a small egg-tooth, which is apparently absorbed, since it is not detachable as in, say, 
young gallinaceous birds. Here, again, there is no trace of separate elements in the 
beak sheath, such as are met with in the petrels for instance, but there is a deep groove 
running from the nares forward, nearer the tomium than the culmen, but this does not 
