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Show 1887.] IN THE LARYNX OF THE ANUROUS AMPHIBIA. 495 their paired nature, which is most conspicuous throughout, remained lor some time a stumbling-block in the way of that interpretation. His however, has shown that the human epiglottis and plicae ary-epiglotticse are formed from a primarily paired structure. He describes them as arising within what he terms the < mesobranchial area,' from ^modification of a couple of conjoined papillate folds or furcula. In other words, the human epiglottis is, according to him, a strictly bilaterally symmetrical structure. Comparison of his description and figures (see especially fig. 44, p. 66, I. c.) with those here given shows that there is no important difference, either in position or origin, between the developing human epiglottis and the epiglottidean folds of the Anura ; but it also introduces a fresh difficulty, on account of the presence in the latter of a couple of tumid Fig. 4. Fig. 5. Fig. 4. The larynx in Ceratophrys americana, 3. Magnified three times. Fig. 5. The same in Calyptocephalus gayi, 3. Magnified twice. References as in figs. 2 and 3. folds below those which 1 have thus far described (* figs. 1 c and 3). These might conceivably represent the furcula of His. They are, however, exceedingly inconstant, and in numerous instances unrecognizable ; fig. 3 represents their maximum development observed. In one instance I noted (R. temporaria, $ , fig. 1 c) that they were asymmetrical, that of the left side being much the smaller of the two2; and this at once suggested that they might be accidental and due to displacement. From careful study of both living and preserved specimens, I am fully satisfied that this is the case. Careful dissection has shown me that they are mere displacements of the mucous membrane, varying with the degree of contraction of the constrictor laryngis and petrohyoid muscles, and I regard them, moreover, as identical with that fold described by Henle in Engystoma, and likened by him to the epiglottis, as already stated. The facts before us go far to justify the view that the epiglottidean folds of the Anura are homologous with the epiglottis of Mammals in its most typical form ; a striking difference, however, suggests itself when comparing the two more closely. The Mammalian epiglottis is always chondrified, and iu direct relationship with the 1 ' Anatomie menschlicher Ernbryonen,' pt. 3, p. 60 et seq. Leipzig, 1885. 2 Insufficientlv expressed in the woodcut, at **. 33* |
