HEEODIONES 



423 



contrasted Ibis and Platalea on the one hand with Ciconia 

 and Tantalus on the other, on account of the following 

 differences : — 



Ihis and Platalea 



Skull sohizorhinal, angle of man- 

 dible produced. 



Pectoralis major single. 



Accessory femorocaudal present. 



Semitendinosus muscular through- 

 out. 



Biceps slip present. 



Ciconia and Tantalus 



Skull holorhinal, angle of mandible 

 truncated. 



Pectoralis double. 



Accessory femorocaudal absent. 



Semitendinosus tendinous for 

 distal half. 



Biceps slip absent. 



To which I add the form of the syrinx. These collec- 

 tively appear to me to justify this separation. The true 



Fig. 198. — Sybinx or Dissura 

 episcopus (aftek Beddabd). 



Fig. 109. — Sybinx or Ahdimia spheno- 

 rhyncha (afteb Beddabd). 



storks, including Tantalus, are well characterised by the 

 peculiar structure of the trachea and syrinx, there being, as 

 already mentioned, an approach in these birds to the purely 

 tracheal syrinx of the tracheophone Passeres. In the 

 common black stork, C. nigra, the syrinx has the form illus- 

 trated in the figure (fig. 197). Its principal features are the 

 absence of intrinsic muscles, the modification of the last 

 tracheal rings, the existence of a rudimentary vocal process 

 (see p. 69), and the closed character of the bronchial rings, 

 which are rings, not semi-rings, the membrana tympani- 



