No. 2.] ON- THE GUSTATORY ORGANS. 1 75 



General Description. — The organ measures 1 5 mm. in length, 

 4.5 mm. in breadth, and 3 mm. in thickness. It is free from 

 the frasnum for 5.5 mm. Papillae of the fungiform type are not 

 numerous. The two circumvallate papillae are on the same 

 transverse line, and are about 3 mm. from the base of the 

 tongue. They are clearly defined, and are 1.2 mm. from each 

 other and about the same distance from the lateral limits of the 

 organ. Their summits are circular, and measure 0.25 mm. in 

 diameter. Serous glands are not abundant. The epiglottis 

 was examined microscopically, but no bulbs were detected. 



The Tongue of Scalops argentatus. 



The material consisted of spirit specimens. 



General Description. — The organ is 25 mm. long, 7.5 mm. 

 wide, and 6 mm. in thickness. The free portion is 13 mm. in 

 length. The papillate surface is somewhat convex, and marked 

 by seven or eight transverse ridges corresponding to the palatal 

 grooves. The tip is rounded. The dorsum is covered with 

 thickly set, simple and compound filiform papillae of the ordinary 

 type. Fungiform papillae are not numerous, but are distributed 

 quite uniformly over the anterior two-thirds of the dorsum. At 

 about 5 mm. from the base of the organ are two elliptical- 

 shaped circumvallate papillae. They are set obliquely to the 

 long axis of the tongue, with their anterior extremity directed 

 outwards. The lateral gustatory structures were not easily de- 

 tectable. They are situated as usual at the sides of the base of 

 the organ, a little anterior to the circumvallate papillae, and con- 

 sist of a few simple, more or less irregular folds of the mucous 



membrane. 



Gustatory Structures. 



The Circumvallate Papillce. — The papillae are lobate. They 

 measure 0.90 mm. in diameter and 0.40 mm. in height. Both 

 serous and mucous glands appear to be plentiful around the 

 papillae. No regular arrangement of the bulbs could be deter- 

 mined from my sections. They measure 0.048 mm. in length 

 and 0.027 mm. in breadth. 



The fungiform papillae are well supplied with bulbs. Some 

 of them are very small, being only about 0.021 mm. in length. 

 They measure on the average, however, 0.035 mm. in length and 

 0.024 mm. in breadth. 



