318 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 
being thicker than on the other side where the valves were relaxed. 
Though I have been unable to detect involuntary muscular fibres, 
it is almost certain that such exist, and that the valves serve to 
prevent the entrance of water and solid particles into the nasal 
passage. Whatever be the mechanism by which the valves act, 
my preparations show that the flaps can, and do, meet in such a 
way as to occlude the air-passages. I trust to be soon in a position 
to unravel the working of the flaps from an examination of the live 
animal. 
Addendum (17th September, 1896).—Although I have not had 
an opportunity of studying the action of the valve in the living 
animal, I have found, in a Platypus just recently killed, that the 
valve acts so perfectly that it is quite impossible to inject water 
‘with a syringe into the nasal passages from the external nasal 
openings. R. B. 
ee 
