74 



H. L. Brunei' 



of water was first forced out of the nostril on the operated side and 

 this was followed by a succession of air bubbles. No air and little, 

 if any, water was lost on the right side. During branchial respiration 

 a strong current of water streamed from the left nostril when the 

 floor of the mouth was elevated; little or none escaped from the 

 right opening — the losses being easily accounted for by the mere 



Fig. 6. 



,-~:~~^ 



Siren lacertina. Transverse section through the choana. ca antorlntal cartilage; t median choanal 



valve. 



closing of the choanal valve. Siinilar results were obtained when 

 the floor of the mouth was elevated in an artificial way. 



The choanal valve of Proteus is similar to that of Necturus, 

 as stated by Anton (1911). 



The Choanal Valves of Siren. 



The inner nasal opening of Siren is accurately located by H. H, 

 Wilder (1889 — 1891) at the outer angle of the mouth between the 

 antorbital cartilage and the pterygo-vomerine bar. Fischer (1864, 

 p. 114) describes the choana as a triangulär opening provided with 

 three valves, which he distinguished by the terms median, lateral 

 and posterior. The posterior valve is said to be furnished with a 

 small muscle by means of which the choana can be opened. Fischer's 

 median valve has also been observed by Seydel (1895, p. 507) and 

 Anton (1911, p. 191). 



