The Amphibian larynx. 283 



Amphiuma (78 mm— 110 mm) which were already in the adult form. 

 From the smallest of these I dissected out the region of the respiratory- 

 cartilages, stained them in alum carmine, and cut a longitudinal series. 

 In this, the arytaenoids were entirely separate, as in the adult, lying in 

 contact with a strip of firm tissue, extending continuously down the side 

 of the trachea as far as the bronchi. Of this strip rather more than 

 the lower two-thirds consisted of hyaline cartilage, but the tissue at 

 the anterior end, and in contact with the arytaenoids showed a struc- 

 ture similar to that of the degenerate fibro- cartilage of Figs. 20, 21, 

 with here and there small groups of hyaline cells. In other words, 

 the conditions were similar to that of the adult, but showed greater 

 continuity of the hyaline tracheal elements. 



The continuity of the degenerate upper end of the tracheal piece 

 with the arytaenoids I have noticed in the adult Siren and in Meno- 

 poma (q. v.) where it is so complete that the hyaline arytaenoids 

 may be described as partly imbedded in the fibro-cartilaginous mass 

 (compare the piece of fibro-cartilage in Figs. 11 and 12 connecting 

 the two hyaline elements). 



The arytaenoids may thus be considered to have the same mor- 

 phological value as the irregular hyaline pieces lower down, although 

 their greater physiological importance has caused them to develop 

 into definite shape before the others. I may thus again emphasize 

 the statement given by Wiedersheim and quoted by me previously 

 (No. 12) that the arytaenoids (i. e. in their fully developed condition) 

 are phylogenetically older than the other respiratory cartilages. 



Siren lacertina. 

 A study of Figs. 13 and 14 will show that we have here essen- 

 tially the same condition as in Amphiuma. Since however, something 

 has already been published respecting Siren, a short treatment of the 

 subject from its historic side would seem advisable. Wiedersheim in 

 his Lehrbuch (1886) describes and figures the tracheal elements of 

 Siren as consisting of many irregular bits of cartilage, which are ar- 

 ranged in two rows anteriorly, but in four posteriorly. ''Das enge 

 Rohr wird in seiner ganzen Ausdehnung von braun pigmentirten, in 

 der Form sehr variirenden Knorpelsplitterchen gestützt, welche bei 

 Siren in der vordem Hälfte der Luftröhre in zwei lateralen, in der 

 hintern aber in vier Serien angeordnet sind". These rows of separate 

 pieces are regarded as primitive, a condition from which that of 

 Amphiuma is derived, "wo sie zu beiden Seiten der nach unten 



