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Show 1906.] RESFIRATORY SYSTEMS IN THE OPHIDIA. 5 2 7 gutter, which extends beyond the commencement of the liver. This band seems to me to present a stage which I have not yet met with in any other Snake, lying between the more usual tracheal gutter and the rudimentary seam, which in a few Snakes (e. g., Python sebce and, which is more to the point at the present moment, Tarbophis) seems to be all that is left to represent the continuation backwards of the trachea within the lung. Tcirbophis obtusus closely resembles Erythrolamprus cesculapii in the structure of its respiratory organs, and both Snakes are placed by Boulenger in the same subfamily of Opisthoglypha. It has a very distinct tracheal lung. This tracheal lung, however, as in Erythrolamprus, is of very modest dimensions. Although it presents the characteristic honeycombed structure only, two or three of the cells intervene between the free ends of the tracheal semirings. The tracheal lung is, in fact, very narrow. The trachea is continued for a short distance into the lung proper, and shortly before its termination gives off a bronchus to the rudimentary left lung. From the point where the tracheal semirings apparently terminate in the interior of the lung a fibrous seam is continued onwards, which recalls at once a very similar seam or ridge in the lungs of the Lacertilian genus Teius* as well as of Python sebce, and of Erythrolamprus just described. In Leptoclira hotamboeia, which belongs, like Erythrolamprus and Tcirbophis, to the Dipsadomorphine family of the Opisthoglypha, the lungs are not widely different from those of Tarbophis. The advantage of examining a recently dead specimen is chiefly seen in the ease with which the vascular can be marked off from the anangious region of the lung. The minute portion of the lung which in this Snake (and others) serves as an efficient breathing-organ, contrasts with the large extent of the functional lung in such a snake as Bitis arietans. There are about 10 inches of vascular lung in the Puff-Adder and about 1^ inches in Leptoclira hotamboeia. Nor is this enormous difference to be explained by relative bulk. Leptodira possesses a rudimentary left lung which in spite of its small size is red, and thus entirely vascular. I have had to remark in other cases upon the vascularity of the rudimentary lung in Snakes. Assuming that the point where the rudimentary lung arises marks the line of division between the thoracic and tracheal lungs, Leptodira may be said to possess a functional tracheal lung. As there is no headward extension of the larger lung, it is not possible to fix the boundary of the thoracic and tracheal lung otherwise. There is, however, an extension of lung-tissue further forward than the very short tract lying in front of the bifurcation of the trachea which is vascular. The tracheal lung is very wide. The membranous interval between the dorsal ends of the tracheal semirings is very much wider than the diameter of the trachea itself. This Snake, therefore, in the * Milano, Zool. Jahrb. Abth. f. Anat. vii. P roc. Z ool. Soc.-1906, No. XXXYI. .36 |