OCR Text |
Show 1879.] TRACHEA OF THE CALLING. 369 tively great depth of the intervals between the lateral parts of the last tracheal and the first bronchial semiring, observed in Thaumalea for instance, not being seen. The first and second bronchial semirings themselves, agreeing as they do with those of Lagopus in all respects, are of the same thickness as their neighbours both above and below-the result being simplicity of construction a little more apparent than real. Many of the bronchial semirings are bifid at tbeir anterior extremities. In the male of Tetrao tetrix the trachea is most extraordinary. At first sight the deeply situated intrathoracic part appears to have Fig. 19. Front view. Tetrao tetrix, <$. no similarity with that of the female, there being developed, on each side, an immense irregular tumefaction, communicating with its fellow by means of a bridge of fatty tissue which covers the anterior portions of the lowermost tracheal rings. W h e n preserved in spirit this tumefaction shrinks to a comparatively small size, to swell to its original bulk upon immersion in water. This leads m e to suppose that it is composed of " mucous " tissue, like that of the umbilical PROC. ZOOL. Soc-1879, No. XXIV. 24 |