388 STRUCTURE AND CLASSIFICATION OF BIRDS 



The ccfc> of C. septentrionalis are conical and saccular in 

 form, with irregular but distinct transverse rugae. 



The syrinx in the divers (Colymbus septentrionalis) is not 

 in any way remarkable in form. The last tracheal rings and 



FIG. 188. SYRINX OF 



i, intrinsic muscles. 



Km. 189. SYEIXX OF 



i, intrinsic muscles. 



the first bronchial are ossified and firmly attached to each 

 other. The pessulus is also ossified. The succeeding bron- 

 chial rings are soft and cartilaginous. The powerful intrinsic 

 muscles are inserted partly on to the last tracheal ring and 

 partly on to the first bronchial, the line of insertion being 

 oblique. 



The syrinx of JEchmophorus (fig. 188) has a very incom- 

 plete bronchidesmus, a very wide space between the two 

 bronchi existing above its anterior edge. The last two 

 tracheal rings are fused to form a long box, into the compo- 

 sition of which it appears to me that the first bronchial semi- 

 ring enters. In any case, if that be not so, the first bronchial 



