34 MAMMALIA. 



the papillae vallatae, in number, position, and size, are subject to 

 the greatest variations. In the Apes the tongue is most like the 

 human organ ; they have from 3 4 7 cup-shaped papillae (p. cir- 

 cumvallatae) ranged in the form of a triangle, or the letter Y ; there 

 are found mostly but 2 or 3, as in the Cheiroptera, in the Horse, 

 Dog, and other Garni vora ; sometimes, however, 10 or more occur. 

 Great and interesting varieties are here exhibited, which have not 

 been followed out so closely as they deserve, since they certainly 

 stand in connexion with the sense of taste, and it is in the 

 papillae vallatae that the glosso-pharyngeal nerve ramifies in particu- 

 lar. Further examples of such varieties may be here adduced. 

 While in Hyaena striata, and Viverra zibetha, there are only two 

 such papillae upon the root of the tongue, and in the Cats, eight dis- 

 posed in two rows, e. g. the Lyon and Lynx ; there are found in Ur- 

 sus arctos as many as 20 arranged in an arciform manner in two rows, 

 the posterior of which is formed of smaller papillae ; 15 in one row 

 are found in Ursus Americanus. Among the Rodentia, Dasyprocta 

 Aguti has a pair of peculiarly large, much elongated papillae. The 

 Goat has 30, 15 upon each side, forming two rows ; the Stag has 

 20 similarly disposed papillae. The 10 to 12 papillae vallatae in the 

 Camel, in which the papillae filiformes also are very long and thick 

 at their roots, are very singularly formed, being large and unequally 

 notched like molar-teeth, arid surrounded by a deep fossa. There 

 rarely lies beneath the tongue a second accessory organ, as in the 

 Bear, or sometimes even a third. 



In addition to the tongue there occur in the Mammalia very pe- 

 culiar organs, probably connected indirectly with the nutritive 

 instincts, and thus with the sense of taste, and which combine the 

 nasal with the oral cavity. These are the Stenonian ducts and 

 Jacobson's organs, so called after their discoverers. The latter 

 sometimes occur when the first are wanting ; though the reverse is 

 more frequently the case. The ducts of Steno are those canals, 

 nearly filled with dense cellular tissue, lined with mucous membrane, 

 and frequently surrounded by cartilaginous sheaths, which lie near to 

 each other, separated by a partition in the intermaxillary bone, behind 

 the incisive teeth ; in the skeleton they pass out by the foramina in- 

 cisiva, which coalesce in Man into a common hole. The naso-pala- 

 tine nerve of Scarpa enters here, and ramifies upon the nasal septum 

 and mucous membrane of the palate. The Jacobsonian organ is 

 particularly developed in the Ruminantia, as in the Stag and Ox, 

 where the trumpet-shaped tubes are above four inches long, and ex- 



