368 STRUCTURE AND CLASSIFICATION OF BIRDS 



each other, and the first two are ossified and somewhat arched. 

 To the first of these are inserted on each side the two flat, rather 

 broad intrinsic muscles, which run side by side, and which 

 appear to be continued by fibrous tissue on to the second 

 semi-ring. There is a normal pessulus. The membrana 

 tympaniformis gets narrower from above downwards (having, 

 therefore, a triangular form), and finally ends opposite the 

 thirteenth semi-ring ; but the rings remain semi-rings after 

 this point, though their ends are very closely approximated, 

 until close to their opening into the lung. G. australasiana 

 shows no special differences. In G. canadensis the two mus- 

 cles, though distinct above, appear to fuse below ; they do not 

 quite reach the bronchial semi -ring as muscle, bat are 

 attached to it by a short ligamentous ending. Grus carun- 

 culata agrees with the last. 



A peculiarity found in many cranes is the convoluted 

 trachea. 1 This state of affairs is not found in Balearica or 

 Aramus. 



In both males and females of the following species the 

 trachea is convoluted : G. cinerea, G. antigone, G. carun- 

 culata, and G. leucogeranos. The males of G. australasiana, 

 and G. canadensis are known to be the same, and the female 

 of G. americana. In the female of G. leucogeranos and in 

 the male of G. carunculata the trachea, though convoluted 

 more or less, does not enter the substance of the sternum, as 

 it does in the others. This too holds good for Tetrapteryx 

 and Anthropoides. 



The trachea has the usual pair of extrinsic muscles, which 

 in Balearica pavonina arise not from the costal processes, as 

 is the rule, but from the angle of the first rib. 



I have myself examined syringes of the following species : 

 Grus canadensis, G. australasiana, G. leucogeranos, G. 

 carunculata, Balearica pavonina, and B. regulorum. 



The syrinx of Balearica is rather different and less 

 typical. 



The two intrinsic muscles are present, but they end in a 



1 See ' A Natural History of the Cranes,' by W. B. TEGETMEIER, and FOKBES, 

 P. Z. S. 1882, p. 353. 



