VOCAL ORGANS. 235 



One of the best accounts we have met with of the 

 vocal organs of birds is by M. Herissant, according 

 to whom the principal apparatus consists of mem- 

 branes varying in thinness and expansion in different 

 species. In such birds as the goose, which is ad- 

 mirably described by Haller*, there are four such 

 membranes, resembling in figure and disposition the 

 reeds of a hautbois, and disposed in twos. But 

 though these membranes, which are more or less 

 distinct according to the species, are the principal 

 vocal organs, they are not the only ones, for M. He- 

 rissant discovered many others in the interior parts 

 of the lungs. They are placed transversely upon 

 one another, and their texture and disposition re- 

 semble spiders' webs. These membranes, so delicate, 

 placed one above the other, and all ready to vibrate, 

 present a spectacle which no naturalist can fail to 

 admire. Each of them is somewhat of a crescent 

 shape, and attached by the circular circumference to 

 the sides of the tube. Each inclines a little towards 

 the end whence the air passes which comes from the 

 lungs, and which cannot pass without exciting them 

 more or less to vibrate. 



Besides the membranes just described, and which 

 are met with in all the birds M. Herissant examined, 

 there are others, of different forms, variously placed 

 over certain bones and cartilages, some being situated 

 towards the middle part of the windpipe, and others 

 lower down. These are also met with in certain 

 water-fowl of the duck tribe. There is found, more- 

 over, in all birds, another membrane varying in 

 thickness, and so essential, that without it no vocal 

 sound could be produced. This is situated almost 

 transversely between the two horns of the crescent- 

 shaped bone (furcida), and there forms the termi- 

 nation of the cavity in the upper and inner part of the 

 * Element. Physiol. 



