The Amphibian larynx. 279 



Proteus anguineus. 



I have observed two adults of this species, the respiratory car- 

 tilages of which are figured in Figs. 11 and 12. In these the position 

 of the degenerate tissue is shown, and its relationship to the hyaline 

 elements. The most noticeable diôerence between this and the fore- 

 going is the presence of large foramina in the triangular portion. 

 These appear to be constant and were so figured by Henle ; but the 

 great individual variation and the probable significance of all such 

 parts (see above, under Necturus) would scarcely allow such a con- 

 clusion. 



In the piece on the left side of Fig. 11, the foramen may be 

 seen to be converted into a notch by the degeneration of its outer 

 wall, while in Fig. 12 (left side) there are two foramina. Henle's 

 farther suggestion that the foramen may denote the place of future 

 separation into the laryngeal and the tracheal elements is refuted also 

 in the same figures, which show that the actual separation of these 

 two elements is at the base of the triangular piece, exactly where, on 

 mechanical principles, the strain would be greatest. 



That these posterior processes are identical with the tracheal 

 elements, may be concluded by a comparison of the relations in 

 Figs. 9, 10 and 13 or 15, Necturus^ Proteus, and Amphiuma or Siren 

 in which Proteus stands in an intermediate position. The processes, 

 short in Necturus, and without connection with the tracheal walls, 

 have lengthened in Proteus until they bound the lateral walls of the 

 entire trachea and are recurved a little upon the lung in the bronchial 

 region. If now we compare Figs. 7 and 12, we can have no reason- 

 able doubt that they are the same posterior processes figured in Nec- 

 turus, while by a comparison with the tracheal cartilages of Am- 

 phiuma, Siren, or any Urodele with a long trachea, the homology is 

 equally plain. My failure to recognize this homology in 1892 was 

 due to the fact that at that time I had never had an opportunity to 

 investigate Proteus and hence had nothing between Necturus and 

 Siren. In the larynx of Proteus as figured by Henle, there is no 

 suggestion of such an homology. I am thus led to abandon my 

 idea of the independent origin of the tracheal ele- 

 ments and revert to that of Henle, as accepted by Gegen- 

 baue. That, however, I am not in accord with these 

 investigators regarding the fate of the tracheal pieces, 

 or with their mode of origin, will appear later. The re- 

 sults obtained from the study of Proteus may be summed up as fol- 



