. Natural history. Geology; Zoology; Botany. SYRINX OP 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 memhrana tympaniformis. The intrinsic muscles terminate in the middle of the ante- penultimate ring, while the e
. Natural history. Geology; Zoology; Botany. SYRINX OP 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 memhrana 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 i-' concerning the rhamphotheca and the ex- ternal nares, the palate, the developing wing and the FIfl. 5.—THE SYBINX OF AN ADULT BMPBEOE PENGUIN, SIDE VIEW, AND IN SECTION TO SHOW THE TEACHEAIi SEPTUM. B = bronoMdesimus; br. = bronchus; s. = septum; tr. = trachea; t. = trachealis muscle; tm. = tympanic membrane. I. = Ist tracheal ring; I.^ = 1st bronchial ring; II. = 2nd bronchial ring. The Rhamphotheca. The shape of the beak in the embryo Emperor Penguin, at the time when the feather papUlse 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
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