RESPIRATORY SYSTEM 



67 



In Menura superba, which has been described by GAEROD, 

 there are three pairs of muscles, which are attached to 

 different bronchia] semi-rings ; the posterior pair of muscles 

 are attached to a ring below that which bears the insertion 

 of the anterior pair, while the remaining middle pair are 

 inserted higher up again. 



We now come to the consideration of those modifications 

 of the syrinx which will be spoken of neither as degenerations 

 nor complications. They are parallel modifications, which 



FIG. 46. THE SAME FKOM BEHIND (AFTER GAKKOI>). 



can in all cases be traced to the typical tracheo-bronchial 

 syrinx, though whether they have originated from it is, of 

 course, a matter of question. To the two varieties of syrinx 

 which we briefly refer to here the names tracheal and 

 bronchial syrinx have been given, implying the fact that 

 the modification of the windpipe has taken place in the 

 one case mainly or entirely in the trachea, and in the other 

 mainly or entirely in the bronchi. 



The tracheal syrinx is distinctive of a group of Passeres 

 which have been on that account called the Tracheophonse ; 



