OCR Text |
Show 378 PROF. A. H. GARROD ON THE [Apr. 1> behind, supported by tbe membranous walls of the windpipe. This is evidently the atrophied fourth ring, counting from below. Above this an abrupt change occurs ; the rings attain their ordinary depth, with only linear intervals between them. The fifth ring, again counting upwards, differs from those above it in being slightly incomplete behind, with downturned ends. The interval between it and the fourth is about equal to its own depth. It in front, and its Fig. 32. Fig. 33. Front view. Back view. Gallus bankiva. superior two or three neighbours behind as well, is slightly V-shaped in the middle line1. The Cracidae are particularly uniform in the manner in which the trachea bifurcates. In 31itua tuberosa there are no tracheal interannular intervals of any kind. The pessulus is united with the penultimate ring posteriorly and with the last ring in front, the latter ring being therefore incomplete behind, as in all the birds above described. Mid-anterior and posterior ossifications extend upwards from the attachments of the pessulus, generally sufficiently high to involve the four lowermost rings, which are therefore consolidated together in the median lines. The lower lateral borders of the last tracheal ring are slightly concave downwards; the medio-anterior descending process being small, whilst by its slightly truncated triangular apex it forms a small portion of the actual margin of the bifurcation. On account of the considerable length of the 1 B y Temminck (loc. cit. pi. ii. fig. 4) a different figure of the windpipe of G. bankiva is given. |