OF THE TONGUES OF THE MAMMALIA. 25 



they are evenly distributed. They are most numerous behind the 

 apex on the dorsum and inferior surface. 



The Lateral Organs. 

 The lateral organs, as in the Chimpanzee, lie on the sides of 

 the tongue, with the upper ends of their fissures and ridges pro- 

 jecting on to the dorsum (text-fig. 7). Each organ is convex 

 inwards, and has both plain and subdivided ridges. The two 

 organs are compared as follows : — 



Right organ : Length *9 cm. Ridges 12. Sulci 13. 

 Left organ : Length "9 cm. Ridges 11. Sulci 12. 



The middle ridges and sulci of the lateral organs are level with 

 the lateral vallate papilla?. 



Lymphoid Tissue. 

 Small and large lymphoid nodules are present on the base of 

 the tongue, and some of the large ones have central pits which 

 are, however, larger than in the Chimpanzee. 



The Frenum. 

 The frenum is short and thick. It runs from the upper surface 

 of the sublingual fold to be inserted into a triangular depression 

 on the under surface of the tongue and from its under surface to 

 the floor of the mouth. 



The Sublingual Fold. 

 The sublingual fold is triangular, and has a bifid apex and 

 crenated edges. 



The White-handed Gibbon (H. lar). 



I examined two preserved specimens (Nos. J. 357.1 & J. 357.2) 

 in the Museum of the Royal College of Surgeons. The former is 

 oval in shape and the latter is conical, but the differences in form 

 are possibly due to varying degrees of muscular contracture. 

 They both differ also in the character of their papilla} and lateral 

 organs. Unless differences are specifically stated here, the 

 characters described are common to both. 



The apex is similar to that of S. syndactylus. 



The lateral borders are full and rounded. They possess both 

 conical and fungiform papilla?, and the latter are very prominent ; 

 some are hemispherical and others are pedunculated. At their 

 posterior extremities the lateral organs are situated. 



No mesial sulci are present on any part of the dorsum. 



The Papillae. 

 The papilla? have the same distribution as in H. muelleri and 

 IT. hoolock, and there is no smooth area on the base of the tongue 

 as in S. syndactylus. 



