1887.] IN THE LARYNX OF THE ANUROUS AMPHIBIA. 495 



their paired Dature, which is most conspicuous throughout, remained 

 for 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 the 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 Ceratophri/s amcricana, cJ . Magnified three times. 

 Fig. 5. The same in Calyptocephalus gayi, (^ . 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 unrecog- 

 nizable ; fig. 3 represents their maximum development observed. In 

 one instance I noted (2?. temporaria, $ , fig. 1 c) that they were 

 asymmetrical, that of the left side being much the smaller of the two "; 

 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 dissec- 

 tion has shown roe that they are mere displacements of the mucous 

 membrane, varying with the degree of contraction of the constrictor 

 laryngis and petrohyoid muscles, and I regatd 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 epi- 

 glottis is always chondrified, and in direct relationship with the 



' ' Anatomie nienschlicher Embryonen,' pt. 3, p. 60 et seq. Leipzig, 1885. 

 '^ Insufficiently expressed in the woodcut, at **. 



33* 



