The Amphibian larynx. 291 



in the case of Pipa by the beautiful figures and descriptions of 

 <jrRÖNBERG (No. 8), which iucludes studies of both sexes. Referring 

 to his work on Pipa, and comparing it with the condition given in 

 Bombinator, we can readily see how his suggestion may have been 

 realized as to the particii)ation of the thyroid processes of the hyoid 

 in the formation of the resonance box. 



In Bombinator, these processes lie so close to the laryngeal ap- 

 paratus that they must materially support and strengthen it, and 

 their nearer approximation and fusion in Pipa to form the "thyroid 

 cartilage" is but a step, especially as the osseous elements remain 

 distinct in the female. An exact regard to homologies, however, 

 would lead me to reject the term "thyroid cartilage" for this newly formed 

 piece, and replace it by hyo-branchial plate, since there can 

 be no homology possible between these processes, secondarily formed 

 from the A.nuran hyobranchial piece (Gaupp, No. 4) and the Mam- 

 malian thyroid (== 2"d and S^'' branchial arches [du Bois, No. 2]). 

 The words of Grönberg in the article quoted, that "so können wir 

 hier zum ersten Mal im Thierreich von einer Cartilago thyroidea im 

 Sinne des Säugethierschildknorpels sprechen", must be taken in a 

 physiological meaning alone. 



The absolutely unique development of the arytaenoids in the 

 male Pipa which hang in the resonance box "wie der Schwengel in 

 der Glocke" (quoted from Mayer, 1825, by Grönberg) is deserving 

 of careful investigation from the side of the physicist, as well as that 

 of the naturalist. The occurrence of actual tracheal rings on the free 

 bronchi is surprising and represents the only case outside of the 

 Gymnophiona where tracheal rings occur within the limits of the 

 Amphibia. Henle's suggestion, previously referred to, of the pro- 

 jecting processes on the tracheal elements of the Urodeles as in- 

 cipient tracheal rings is unsatisfactory, and we must seek their origin, 

 here and elsewhere, in the embryological development. 



I strongly suspect, however, that the tracheal rings of the reptile, 

 inherited from them by the other Amniota, are not strictly homolog- 

 ous with these chance occurrences among the most specialized Am- 

 phibia; but a clue to the mechanics of the formation in any case 

 would be helpful and a distinct advance towards the solution of the 

 problem. 



The laryngeal apparatus of Bactylethra is markedly different 

 from that of Pipa^ great changes in the formation of the resonance 

 ijox being occasioned by a ditiefent disposal of the hyoid elements. 



Zool. Jahrb. IX. .Vbtli. 1. Horpli. 2U 



