498 PROF. G. B. HOWES ON AN UNRECOGNIZED FEATURE [Juue 7, 



it (figs. 6 to 10) in all its important aspects. The interest of it is 

 ■vastly increased when it is stated that in a female which I have exa- 

 mined the folds were absent, while in a second male they were 

 insignificant ' — facts which point to the conclusion that their develop- 

 ment takes place comparatively late in life, in all probability corre- 

 latively with sexual maturation. 



Fig. 8. 



The larjnx in Chiroleptcs australis, side view. 



Fig. 9. 



The same, in longitudinal section. 



Eeferences as in previous iJgures. c.a, right arytenoid ; c.lt, cricoid (laryngo- 

 tracheal) cartilage ; ht/, body of hyoid ; m.(/h, genio-hyoglossus muscles ; 

 pc, pericardium; j)^, entrance to right luug; s.ff, gular sac; vc, right 

 vocal cord. 



Figs. 6 to 9 will show how fully the two structures may be de- 

 veloped. The epiglottis, eg., stands out prominently in front ; the 

 epilaryngeal fold is hood-shaped, overhanging the hinder third of the 

 aditus, and the two together embrace the lateral walls of the aditus 

 for nearly its whole extent — so much so, that I at first took them to be 

 continuous. This, however, is not the case, and here, as in all other 

 examples with w'hich I have met, the two structures, although they 

 may approximate, are perfectly distinct (cf. fig. 5). The epilaryngeal 

 fold is entirely membranous, exhibiting on its upper part, which is 



^ For the opportunity of examining these two specimens, as for further 

 assistance, I am indebted to the courtesy of Mr. Eoulenger, F.Z.S., of the 

 National Museum at South Kensington. 



