No. 2.] ON THE GUSTATORY ORGANS. 17 1 



unusually long necks, and apparently reach the free surface. 

 The mucous glands of Nuhn are present in the tip of the 

 tongue, their ducts opening on its inferior surface. The epithe- 

 lium of the larynx was searched for bulbs, but none were 

 detected. 



In many ways the gustatory structures of Castor fiber d^-^-^xf^-dich. 

 closely those of Arctomys nionax. 



The Tongue of Cynoniys ludoincianiis . 



The material consisted of two specimens. One of the tongues 

 had been kept in dilute spirit, and was gradually hardened in 

 ordinary spirit and absolute alcohol. The other tongue, a fresh 

 specimen, was prepared for microscopical examination by the 

 method employed for Lepiis and Castor. 



General Description. — The organ is 41 mm. in length, 11 mm. 

 in breadth, and 8 mm. in thickness. The free portion measures 

 16 mm. in length. The papillate surface is wrinkled anteriorly, 

 and soft and velvety to the touch. The tip is obtuse, and 

 slightly cleft as in Arctomys, Fiber, and Hcsperomys. The 

 fungiform papillae are small and inconspicuous, but are quite 

 evenly distributed over the anterior third and tip of the tongue. 

 The filiform papillae resemble those of Fiber. The under sur- 

 face of the organ is impressed by a deep central groove. The 

 circumvallate papillae are three in number, and are situated 

 well back on the dorsum. They are arranged in an isosceles 

 triangle, the apex of the triangle being directed backwards. 

 The posterior papilla is 3.5 mm. from the base of the tongue. 

 The lateral gustatory organs are situated somewhat further 

 forward than the circumvallate papillae. When viewed from 

 above, they present a row of slit-like openings, below which 

 are a number of mound-like elevations. Each elevation is 

 pierced near its centre by a small aperture, which proved on 

 closer examination to be the mouth of a mucous duct. Above 

 the lateral taste organ is a fringe of filiform papillae, the points 

 of which are directed upwards, inwards, and backwards. The 

 fringe is continued on to the lower part of the glosso-palatine 

 arch. 



Gustatory Structures. 



The Circumvallate Papillce. — The lingual surface adjacent to 

 the papillae is slightly papillate. The papillae are of good size 



