No. 2.] ON THE GUSTATORY ORGANS. 163 



Gustatory Structures. 



The Circumvallate Papillcs. — The two papillce required the 

 aid of a powerful lens to reveal their presence. They are as 

 usual on the same transverse line, 1.7 mm. apart, and lie com- 

 pletely concealed in deep and narrow trenches, their apices, 

 which are inclined inwards towards the median line, being 

 slightly below the openings of the latter. At a short distance 

 above their bases (which are constricted) the papillse measure 

 0.23 mm. in diameter, their height being 0.6 mm., or nearly 

 three times the transverse diameter. I do not think it probable 

 that the mouths of the trenches can be closed. The arrange- 

 ment of the muscles beneath the papilte suggests a possible 

 drawing downwards of the entire region, but not of the papillse 

 alone. Glands of the serous type are sparingly scattered 

 through the connective tissue stroma underlying the papilte, 

 and their ducts open into the trenches at various levels. 



The bulbs are restricted to the lower two-thirds of the lateral 

 area of the papillae. There may be seventeen or more tiers of 

 them. They were not clearly enough defined for me to deter- 

 mine the mean dimensions of the typical bulb of this species. 

 One which I measured, and which was probably somewhat below 

 the mean, was 0.030 mm. in length and 0.018 mm. in breadth. 

 No lateral organs of taste were found on this piece of tongue. 



The circumvallate papillae of Chlamyphorns approach quite 

 closely the marsupial type, the resemblance between them and 

 the anterior papillae of Belideus and Phalangista being very 

 marked. 



The Tongue of Lepiis campestris. 



I received a fresh specimen of this tongue. The organ was 

 placed in a mixture of five parts Muller's fluid and one part 

 alcohol. After remaining in this mixture for fourteen days, it 

 was washed for a few hours in running water, and then trans- 

 ferred to ordinary spirit, where the hardening was completed. 



General Description. —In many rodents the posterior portion 

 of the tongue rises somewhat abruptly above the level of the 

 anterior. This is a characteristic feature of the tongue of 

 Lepus. The organ shows two well-marked divisions, a more or 

 less flattened and expanded anterior portion, and a raised pos- 



