RESPIRATORY SYSTEM 



69 



bouring 



rings 



for instance (see fig. 47), the lowest seventy-eight rings of the 

 trachea are modified through being thinner than those else- 

 where, and this portion of the tube is of a greater calibre than 

 that above. In Cicoina alba the lowest twenty-nine rings are 

 thus changed in structure, and ' there is a small prolongation 

 upwards of the lateral portions of the three lowermost 

 tracheal rings, which forms a consolidated triangular process 

 on each side, overlapping the next few rings and looking 

 extremely like the rudiment of the similarly situated proces- 

 sus vocales of the passerine 

 tracheophone syrinx, which 

 resemblance is increased by 

 the thinness of the neigh- 

 aiid by their 

 from before 

 backwards.' 



The bronchial syrinx is 

 seen in its most extreme de- 

 velopment in Steatornis and 

 in Crotophaga, where it was 

 originally described by MUL- 

 LER ; but other cuckoos and 

 goatsuckers, as has been 

 shown by me, 1 possess also 

 a syrinx which may be 

 called bronchial ; further- 

 more, as WUNDEELICH has 

 shown, 2 the ow r l tribe resem- 

 ble the goatsuckers in this 



being flattened 



FIG. 48. SYRINX OF Steatornis. FRONT 

 VIEW. (AFTER GARROD). 



respect, while there are in- 

 dications of the bronchial syrinx in certain petrels. 



The fullest description of the syrinx of Steatornis, which 

 we take as a type of the perfectly formed bronchial syrinx, 



1 ' On the Syrinx and other Points in the Anatomy of the Gaprimulgidse,' 

 P. Z. ,S'. 1886, p. 147 ; ' On the Structural Characters and Classification of the 

 Cuckoos,' P. Z. S. 1888, p. 168. 



- 'Beitriige zur vergleichenden Anatomie und Entwickelungsgeschichte des 

 unteren Kehlkopfs der Vf^el,' Nor. Act. Acad. Leop. Cces. 1884. 



