OCR Text |
Show 1875.] PROF. W. H. FLOWER ON THE MUSK-DEER. 165 Fig. 3. Epiglottis and opening into larynx, natural size. The thyroid body is much flattened and oval and of very loose texture, extending from the top of the first tracheal ring to the bottom of the eighth, 0"*8 long and 0"*4 across at the thickest part. The number of rings in the trachea, above the part where the branch to the upper right lobe of the lung is given off, is 49, between this branch and the bifurcation 11 ; total 60*. Some of the rings are single at one side and bifurcated at the other; thus the third ring is single on the left and double on the right side, and the succeeding ring has the opposite arrangement. These double rings have been counted as two in the enumeration given above. Thoracic Viscera. The hinder margin of each lung is entire. The lower lobes are nearly equal in size (the left slightly the largest), of the usual triangular form, being divided off from the rest of the organ by a nearly horizontal fissure, which does not extend quite to the root of the lung behind, though further on the right than the left side. Near the upper part of the inner border of the right lobe, attached by a narrow neck, is the so-called " azygos lobe " (fig. 4, A) deeply fissured on its anterior surface. Above the horizontal fissure the arrangement on the two sides is very different. On the right side there are two distinct lobes, the cleft between them extending almost to the root of the lung; the upper one (B (7) roughly triangular, with the apex upwards and supplied with air by the upper branch of the trachea. It is constricted across its middle into an upper and lower portion. The lower one, or middle right lobe (B M), is tongue-shaped, with its apex directed forwards, and while connected at its base with both the upper and lower lobes, it receives its main supply of air from a branch from the principal right bronchus. The upper portion of the left lung consists of a single lobe (L U), but with a short cleft on its anterior border, dividing it partially into a long, narrow, tongue-shaped, inferior portion, with the apex projecting forwards and corresponding to the middle lobe of the right side * In the Pudu the number of rings of the trachea is almost exactly the same as in Moschus. I counted fifty above and ten below the upper right bronchus. |