96 AVES. 



(otolhhs) are found, as in Man and Mammalia. The diversities pre- 

 sented by the auditory apparatus in the several orders and genera "can 

 not be entered upon in a work like the present. The Struthious 

 birds appear to agree essentially with the other members of the class 

 in their organs of hearing, only their conical cochlea is the smallest 

 in size in proportion to the other parts. 



Organs of Smell. 



The ethmoid bone in Birds forms an osseous plate of considerable 

 size (frequently interrupted by an aperture closed with membrane), 

 which is interposed between the orbitar cavities, and presents 

 generally rudiments of lateral parts. This bony septum is completed 

 in front by cartilage. The nasal cavity is remarkably large ; a 

 proper external moveable nose is, however, wanting, and the nostrils 

 are situated upon the upper mandible near to the base of the bill, 

 being wide and distinctly visible ; but in rare instances, as in the 

 Booby (Sula alba), they are so narrow that they have been errone- 

 ously believed to be wanting altogether. Cartilaginous but immove- 

 able nasal alae are for the most part present, and occasionally, as in 

 the Albatross, Petrel, and Puffin, elongated into a tube which may 

 be regarded as an external nasal organ. The nostrils vary in form 

 and size, and are frequently, as in the Raven, protected with feather- 

 like bristles. The two nostrils are separated from each other by a 

 septum, which, is wanting however in many birds, e. g. the Gallinazo 

 (Cathartes), so that they intercommunicate from either side. The 

 posterior nasal orifices (choance) are two long narrow fissures fre- 

 quently coalescing into one, at the commencement of which in the 

 palate are usually found some epithelial papillae. Within each 

 nasal cavity are situated three cartilaginous, rarely partly ossified, 

 turbinated bones ; the superior of these is formed by a simple 

 spheroidal or bell-shaped inflexion of the lateral cartilaginous pa- 

 rietes of the nasal cavity ; the inferior frequently consists of a 

 small curved plate provided with lateral projections, which adheres 

 to the septum narium and is often largely developed, as in the Snipe, 

 where it is represented by a falciform lamina. The middle one, 

 which is the largest in size, is to be regarded as a true turbinated 

 bone, being constantly a perfectly convoluted cartilagino-membran- 

 ous plate varying in its degree of development. Among birds of 

 the Duck kind, its convolution makes two and a half turns, in the 

 Gallinse only one and a half ; accessory nasal cavities or sinuses are 



