KESPIRATORY SYSTEM 



69 



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

 trachea are modified through being thinner than those else- 

 ■Wheie, and this portion of the tube is of a greater caHbre than 

 that above. In Ciconia 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- 

 bouring rings and by their 

 being flattened from before 

 backwards.' 



The bronchial syrinx is 

 - seen in its most .extreme de- 

 velopment in Steatornid. and 

 in Crotophaga, where it was 

 originally described by MiJiJ- 

 LBE ; but other cuckoos and 

 goatsuckers, as has been 

 shown by me,' possess also 

 a syrinx which may be 

 called bronchial ; further- 

 more, as WuNDBRLiCH has 

 shown,^ the owl tribe resem- 

 ble the goatsuckers in this Fig. 48 

 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. 



Strinx of steatornis, Fkont 

 View. (Apteb Gakbob). 



' ' On the Syrinx and other Points in the Anatomy of the OaprimulgidBS,' 

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

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



^ 'Beitrage zur vergleichenden Anatomie und Entwickeluugsgeschichte des 

 unteren Kehlkopfs der Vogel,' Nov. Act. Aqad. Leop. Cms. 1884. 



