STRUTHIONES 



507 



which are the outward expression of a reticulate internal 

 structure, like a ruminant's stomach. Towards the extremity 

 of the caecum the folds cease to be so definitely arranged in 

 a network, and some to present an indication of a spiral dis- 

 position. Rhea has also very large caeca, and there are 

 traces of the spiral valve of the ostrich. The caeca of the 

 cassowaries and the emu, as will be seen from the table of 

 measurement, are very much smaller than those of the 

 ostrich and Rhea. GADOW mentions an obscure formation of 



FIG. 235. SYRINX OF Apteryx FIG. 236. THE SAME, FROM BEHIND. 



Mantelli. FRONT VIEW. 

 (AFTER FORBES.) 



o.oo, ill this and following 

 figs., tracheal rings. 



an internal network by the presence of folds which may be 

 compared with the structure of the caeca of Calodromas, 

 already referred to. The caeca of Apteryx are long and nar- 

 row, like those of the tinamous (excluding Calodromas) . 



Struthio has the most remarkable liver of all the Stru- 

 thiones. The two lobes are intimately fused into one heart- 

 shaped lobe. There is an indication of a spigelian lobe, as 

 with other Struthiones, and the single bile duct (there is no 

 gall bladder) opens, exceptionally, only 4 cm. from the 

 pylorus. Ehea has, as a rule, no gall bladder, but GADOW 

 found traces of one in a specimen dissected. This occurred 

 (see figs. 19, 20, p. 34) both in Eli.Darwini and Eh. americu-n. 

 Casuarius and Dromceus have a well-developed gall bladder, 



