AIR-SACS 



753 



Pjp^. 45i._Diagram of air-sacs of a pigeon.— From an injected 



Specimen. 



TR., Trachea ; S., syrinx ; BR., bronchial tubes ; /-C^-v^'^SjtlcS- 

 air-sac, with a branch entering "f hiimerus (H.) C cenacal air 

 sac giving ofi minor saccules M.C.) i" the neck; TH.I., hrst 

 thoracic- TH.//., second thoracic; ABD., abdominal a.r-sac. 



48 



