124 



STRUCTURE AND CLASSIFICATION OF BIRDS 



formis being absent. In Xenorhynchus senegalensis, 1 how- 

 ever (fig. '200), there is some approach to the more typical 

 tracheo-bronchial syrinx, which is further developed in 

 Abdimia sphenorhyncha and Dixsii-ra episcopus ; l the 

 syringes of these two storks are illustrated herewith (figs. 199, 



FIG. 200. SYRINX OF Xenorhynchus scncyalensis (AFTER BEDDAED). 



198). In the former as well as in the latter the intrinsic 

 muscles are still absent, and there is a considerable modifi- 

 cation of the last tracheal rings ; but in both there is a 

 partial deficiency of cartilage where the membrana tympani- 

 formis is developed in other birds. In Xenorhynchus this 



1 F. E. BEDDARP, ' A Note upon Dissura episcopus,'' &c., P. Z. S. 1896, p. 231. 



