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Show 384 MR. W. A. FORBES ON THE [May 4, where it is well developed, the last ring being here notched above. Behind, the ultimate and penultimate rings are united by a vertically disposed median bar. The last ring forms a three-way piece, there being a forwardly-directed narrow pessulus developed from its hinder margin below. The pessulus is apparently membranous, in this specimen at least, except at its base. The first bronchial semirings are still narrower than the last tracheal one and strongly arched, being concave downwards. They are separated by a very slight interval indeed from the last tracheal ring (three-way piece), and are nearly in contact with each other in front in the middle line ; behind they are inturned and somewhat thickened. To the middle of each ring, or a little posteriorly to this point, is attached the lateral tracheal muscle, Fi°* 2. Syriux of Eurylamus ochromelas, X 5, viewed from in front. p, the " pseudo-ring." which is extremely slender and hardly visible when dry. The second bronchial semirings are shorter than either the first or third ; they are slightly deeper than the first pair, but are narrowed behind. Being only slightly concave downwards, a considerable membrane-covered fenestra is left between them and the first pair. What at first looks like a bronchial semiring is interposed between what are here described as the first and second of that category. This pseudo-ring is most evident in front (vide fig. 2), but is also visible when dry behind ; it is apparently due to the accumulation of tissue inside, forming the outer boundary of each glottis. The third and fourth rings are slightly concave upwards : they are deeper, especially behind, thinning away towards the front, than those that preceded them. The fifth and other succeeding rings are typical, unmodified bronchial rings, which more and more encroach upon the membrana tympaniformis, and eventually almost overlap behind. The second and succeeding semirings are more or less incompletely ossified at their ends. In Cymbirhynchus macrorhynchus (figs. 3-5), the syrinx is constructed on essentially the same plan, with some modifications. The trachea, below the insertion of the extrinsic muscles (on the last ring but six), appears to be somewhat laterally compressed and diminished in size. In the specimen before m e the last few tracheal rings are somewhat irregular in their disposition, |