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Show 526 ON T H E A N A T O M Y O F PASSERINE BIRDS [June 5, fied, except the last, which is developed into a three-way piece from the presence of a bar running from before backwards at the middle of the lower margin. The first bronchial half-ring is of the same flattened and deep nature as the tracheal rings, and, like them also, is not separated from the three-way piece by any interval. To its anterior end, on each side, as well as to the front of the three-way piece, the intrinsic muscle is attached, which descends, broad and thin, down the front of the lower part of the trachea, in contact with its fellow of the opposite side, there to terminate (vide Plate LIII. fig. 8). The second bronchial semi-ring is not modified. It is separated by a. short interval from the first, and by a strikingly considerable one from the third, which is the commencement of the normal bronchus. I could not find that the muscles of the syrinx sent any fibres to this second ring, as in Pachyrhamphus atricapillus, described by Miiller, although otherwise this structure is almost identical in the two birds. If they are present they must be extremely feeble; and the relative distances of the upper bronchial semi-rings favours the view that some special arrangement exists. The account, above given, of the voice-organs in the aberrant Passeres in question, is entirely confirmatory of the results arrived at by Johannes Miiller. Both Hylactes and Grallaria are completely tracheophone, as he predicted they would be found to be, although they agree with one another, and differ from those previously described in having the syringeal end of the trachea less abruptly distinguishable as being composed of two parts. Neither Lipaugus, nor Heteropelma, nor Hadrostomus are far from the mesomyodian types already known, as far as their voice-organs are concerned, which structure clearly shows that our nomenclature is an inefficient one when it places Hadrostomus as far from Pachyrhamphus as either is from Tityra. Again, also, that the Pipridse and Cotingidar should be considered to be different families is not borne out by the nature of the lower larynx ; and it seems hardly possible to allow a difference in tarsal scutellation to constitute a family difference, when not borne out by more important points of internal structure. EXPLANATION OF PLATE LIII. Fig. 1. Syrinx of Grallaria guatemalensis, front view. 2. The same, back view. 3. The same, lateral view, from within, showing the fusiform processus vocalis. 4. Syrinx of Hylactes megapodius, front view. 5. The same, back view. 6. Syrinx of Lipaugus cineraceus, front view. 7. The same, side view. 8. Syrinx of Hadrostomus aglaia, front view. |