1874.] 



VOMITED B\ HORNBILLS. 



421 



geons' Museum, and mounted as preparations. Professor Flower 

 carefully examined and compared the above. 



In his notice of the object (P. Z. S. 1869, p. 150) he found the 

 stomach possessing its apparent natural coat. Whence, therefore, 

 had the other come? He confirmed my statement of the identity in 

 structure of the expelled sac and the internal epithelial layer of the 

 cavity of the gizzard. Both behaved the same to chemical reagents ; 

 microscopical sections of each exhibited a like matrix slightly lami- 

 nated with scattered nuclei and granules. He failed, however, in 

 either to detect the definite structures ascribed to the inner coat 

 of graniferous birds. 



There still remain some obscure and hitherto unexplained points 

 connected with the production of these anomalous food-bags, which 

 it is the purport of the present paper to unravel. However incon- 

 gruously it may sound, Mr. Bartlett and myself were both right and 

 both wrong — he correct in suspecting the substance to be a peri- 

 odical regurgitation normally coincident with the process of incuba- 

 tion, in error in believing it to be a secretion derived from the pro- 

 ventriculus or glands opening into the alimentary canal above that. 

 I was justified in its being the epithelial layer of the gizzard, but 

 deceived as to its being cast off through morbid influences. 



From indubitable evidence on the habits of the wild birds and 

 frequent occurrence of the phenomenon in specimens in the Society's 

 Menagerie, as described by Mr. Bartlett, there is validity in assum- 

 ing that the vomiting of food enclosed in a horny sac is common to 



Fig. 1, 



Empty gizzard-sacs ejected by the Subcylindric.il Hornbill, 



Buccros subcglindricus, about natural size. 



