1874.] MR. A. H. GARROD ON THE AUSTRALIAN BUSTARD. 4/3 



very similar in appearance, in closely allied birds, may be the result 

 of different mechanisms. In the feet of the Cuculidce and the Picidas 

 the scansorial arrangement of the toes is the result of entirety 

 different dispositions of the tendons which move them ; and in Otis 

 tarda and Eupodotis australis the same reasoning holds. 



In both these birds there is, during the show-off, a distention with 

 air of a well differentiated bag, which is in both cases lined with a true 

 mucous membrane. But in Otis tarda this sac is a special structure 

 in front of the windpipe, opening under the tongue ; whilst in Eupo- 

 dotis australis (in the specimen under consideration at least), it is 

 simply a highly dilated oesophagus. 



Through the kindness of Lord Lilford I am in possession of an 

 excellent Spanish specimen of the gular pouch of Otis tarda (see 

 fig. 1, p. 472), with the whole of the oesophagus, the tongue, and 

 part of the trachea attached. In it the gular pouch, opening sublin- 

 gually, is capacious, and, when distended, egg-shaped with no con- 

 striction in any part. The cesophagus is uniformly cylindrical for 

 its upper two thirds, and not at all enlarged. Lower down there is 

 a well-developed globular crop. 



In the specimen of Eupodotis australis which died on May 1 1, as 

 previously mentioned, there is no trace of a gular pouch. The 

 cesophagus is enormously dilated from its commencement (see fig. 2, 

 p. 472), and gives no indication whatever of any division into tube and 

 crop. Its greatest circumference, when fairly inflated, is 14 inches, 

 and the length of the distended portion of the tube is 17g inches. 

 Before dissection, by filling its cavity with air, the lower portion of 

 the dilated cesophagus protruded downwards considerably in front of 

 the t symphysis furculce, and formed the depending portion of the sac 

 which was so conspicuous in the living animal. The trachea de- 

 scended in front of this sac ; and when the latter was undistended, the 

 former, on account of the diminished distance between the points it 

 had to reach, was zigzagged from side to side in the part opposite the 

 pendent portion. The keeper, J. Church, tells me that, when 

 handling the sac in the living bird, he always felt a hard cord 

 running down in front of it, which was evidently the windpipe. The 

 dilated oesophagus was, as might have been expected, covered with 

 two coats of muscular tissue, the outer longitudinal — and the inner 

 transverse. The mucous lining presented no peculiarities. The 

 skin in front of the neck was lax, with a considerable amount of 

 coarse fat in its deeper layer ; it was engorged with blood, tortuous 

 vessels running through it in all directions. 



I may mention as an anatomical peculiarity of interest that Eupo- 

 dotis australis and E. denhami possess but one carotid artery, the 

 right — a condition I have not seen in any other bird ; Otis tarda and 

 O. macqueeni have two, and Tetrax campestris the left only. 

 Most probably the presence of a right carotid only is characteristic 

 of the genus Eupodotis. 



Proc. Zool. Soc— 1874, No. XXXI. 31 



