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Show 1887-] IN THE LARYNX OF THE ANUROUS AMPHIBIA. 493 hinder border of the body of the hyoid. This was so in the specimen to which I have just referred, and the anterior prolongation described overhung this depression, in a manner strikingly suggestive of the epiglottis. Holl * and Royer and Bambecke2 have most recently studied the anatomy of the mouth in the Anurous Amphibia : tbe first-named author deals chiefly with histological details in R. temporaria ; the last-named deal with the subject in general; but I fail to find mention, in their writings, of those facts with which I am concerned. I am satisfied that the structures described above may or may not be present in individual examples of the common Frog, and have found, to m y surprise, that the free anterior extremity of the larynx is subject to no inconsiderable amount of variatiou in it, to say nothing of the Anura as a group. If the lips of the laryngeal aditus be examined with care in JK. temporaria there will generally be found at its anterior end folds identical with those here figured, but more or less marked. They are sometimes so small that there is little wonder they should have been so long overlooked. They are well differentiated from the rest of the larynx ; of a yellowish colour in life and soft and fleshy, projecting freely beyond those parts which are supported in cartilage (cf. figs. 1, 1 a, eg). There generally passes between them a thin transverse fold of mucous membrane, and occasionally, when very minute, they are, together with the same, erected and closely applied to the front face of the larynx (figs. 1 b and 6). I was for some time disposed to think that they might be peculiar to the males; but that this is not the case the larynx of an adult female, represented in fig. 1 c, will show. That specimen is further remarkable, among the larynges of a number of females which I have examined, for the fact that the folds were continued along the sides of the aditus, the anterior half of that being thus embraced by a hood-shaped lip. On examining other members of the group, it early became obvious that the structure with which we here have to deal was by no means exceptional. In Leptodactylus pentadactylus and the Bull-Frog (R. pipiens), for example (figs. 2 and 3), two papillate elevations were found to be present; these were in both cases small and erected, and united by a transverse fold as in the first-named example. Comparison of figs. 1 b and 2 reveals an absolute identity between individuals of R. temporaria and Leptodactylus pentadactylus. In two of the above-named species 1 found, in addition to the foregoing, a couple of other folds which were related to the hind half of the aditus (ep, figs. 2 and 3). In the Bull-Frog (fig. 3) they passed insensibly into the mucous membrane posterior to the larynx ; but in Leptodactylus (fig. 2) they united behmd so as to form an insignificant lip which embraced the hind boundary of the aditus, much as did the supposed epiglottis its front one. I have not seen 1 Sitzungsb. Wien. Akad., Jan. 1887. 2 " Sur les caract. fournis par la bouche des tetards des Batraciens anoures d'Europe " Bullet, Soc. Zool. d. France, 1881, p. 75. PKOC. ZOOL. Soc-1887, No. XXXIII. 33 |
