310 AVES. 



the orbit, the external terminates behind the his experiments, birds enjoy the sense of smell, 



middle turbinated lamina in a cul-de-sac, beginning with those in which it is most acute: 



These olfactory lamince differ in regard to tex- Grallatores, Natatores, Haptores, Scansores, 



ture. In the Cassowary and Albatross they Intctsores, Rasores. 



are said to be membranous. Cuvier states that There is still, however, much obscurity 

 they appeared to him to be bony in the Horn- with reference to the extent to which Birds 

 bill and Toucan. We have found this to be the make use of their olfactory organs. It has 

 case in the recent Toucan. The organ of smell in been generally asserted that birds of prey are 

 this singular species is confined to the base of its gifted with a highly acute sense of smell, and 

 enormous beak, (7Z,eJ*g. 150.) The canal, which that they can discover by means of it the 

 is traversed by the air and odorous particles in carcass of a dead animal at great distances ; 

 inspiration, forms a sigmoid curve in the vertical but those who have witnessed the rapidity with 

 direction. The external orifice is on precisely which the Vu'.tures descend from invisible 

 the same perpendicular line as the internal, heights of the atmosphere to the carcass of an 

 or, as it is generally termed, the posterior nasal animal, too recently killed to attract them by 

 aperture. The external nostril (d, Jig. 150) putrefactive exhalations, have generally been 

 being situated on the posterior surface of the led to consider them as being directed to their 

 upper mandible, where it is raised above the quarry by sight. " That this is the case," Dr. 

 level of the cranium, is consequently directed Koget observes, " appears to be now suffi- 

 backvvards, secure from all injury to which it ciently established by the observations and 

 might be exposed while the bill was used in experiments of Mr. Audubon, which show that 

 penetrating dense and interwoven foliage, these birds in reality possess the sense of smell 

 The olfactory canal is at its commencement in a degree very inferior to carnivorous quadru- 

 of a cylindrical form, and about two lines in peds, and that so far from guiding them to 

 diameter. It passes forwards for about half an their prey from any distance, it affords them no 

 inch, receiving the projection of the first spongy indication of its presence even when close at hand, 

 bone, then bends downwards and backwards, The folio wing experiments appear to be perfect- 

 and is dilated to admit the projections of the ly conclusive on this subject. Having pro- 

 two other spongy bones. From this point it cured the skin of a deer, Mr. Audubon stuffed 

 descends vertically to the palate, at first con- it full of hay ; after the whole had become 

 traded and afterwards dilating to form the in- perfectly dry and hard, he placed it in the mid- 

 ternal or posterior orifice, (e,fg. 150.) The die of an open field, laying it down on its back 

 first or outermost spongy bone is almost hori- in the attitude of a dead animal. In the 

 zontal, and has its convexity directed outwards, course of a few minutes afterwards he observed 

 The second is nearly vertically placed, with its a vulture flying towards and alighting near it. 

 convexity directed backwards : it terminates in Quite unsuspicious of the deception, the bird 

 a narrow point below. The superior spongy immediately proceeded to attack it as usual in 

 bone is about the size and shape of a pea. the most vulnerable points. Failing in this 

 All these bones are processes from the inner object, he next with much exertion tore open 

 and posterior parietes of the nasal passage; the seams of the skin where it had been stitched 

 they are cellular, and air is continued into together, and appeared earnestly intent on get- 

 them from the cranial diploe ; but the parietes ting at the flesh, which he expected to find 

 of the nasal passage are entire and smooth, within, and of the absence of which not one 

 and lined by a delicate pituitary membrane, so of his senses was able to inform him. Find- 

 that there is no direct communication between ing that his efforts, which were long reiterated, 

 the cells, the turbinated bones, or of the man- led to no other result than the pulling out large 

 dible and the nasal passages. quantities of hay, he at length, though with 

 In most birds the nasal cavities communicate evident reluctance ? gave up the attempt, and 

 with the pharynx by two distinct but closely took flight in pursuit of other game to which 

 approximated apertures. In the Cormorant, he was led by the sight alone, and which he 

 however, these join into one before their termi- was not long in discovering and securing, 

 nation posteriorly, which is consequently by a " Another experiment, the converse of the 

 single aperture. The olfactory nerves are dis- first, was next tried. A large dead hog was 

 tributed exclusively to the pituitary membrane concealed in a narrow and winding ravine, 

 covering the septum narium and the superior about twenty feet deeper than the surface of 

 spongy bone. The pituitary membrane is of the earth around it, and filled with briers and 

 the most delicate structure, and is most vas- high cane. This was done in the month of 

 cular, where it covers the superior turbinated July, in a tropical climate, where putrefaction 

 lamina, and becomes thicker and more villous takes place with great rapidity ; yet, although 

 as it descends upon the middle one. It every- many vultures were seen from time to time 

 where displays numerous pores of muciparous sailing in all directions over the spot where the 

 glands, which bedew it with a lubricating putrid carcass was lying, covered only with 

 secretion. twigs of cane, none ever discovered it; but in 

 According to Scarpa the acuteness of smell the meanwhile several dogs had found their 

 is exactly in proportion to the development of way to it and had devoured large quantities of 

 the superior turbinated lamina, to which the the flesh."* 

 size of the olfactory nerve corresponds. The 

 following is the order in which, according to * See Roget, Bridgewatcr Treatise, vol. it. p. 406. 



