-424 STRUCTURE AND CLASSIFICATION OF BIRDS 



formis being absent. In Xenorhynchus senegalensis,^ how- 

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

 tracheo-bronchial syrinx, which is further developed in 

 Ahdimia sphenorhyncha and Dismra episcoptis;^ the 

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



FiQ. 200. — Sykinx of Xenorhynchus senegalensis (aftbe Beddard). 



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 tympanic 

 formis is developed in other birds. In Xenorhynchus this 



' r. E. Beddakd, ' A Note upon Dissura episcqpus,' &c., P. Z. S. 1896, p. 231. 



