OP THE TONGUES OF THE MAMMALIA. 19 



The conical papillae on the base increase in size from before 

 backwards, but they never attain the degree of development 

 which is exhibited on the tongues of the Chimpanzee or Gorilla. 

 They belong to the cylindrical type, and many of the large ones 

 at the base have long hair-like processes. These basal papillae 

 are arranged in two groups — ^one on each side of the non- 

 papillary area. 



No foramen ccecu7n, lytta, oy plicce fimbriatce are present. 



The Lateral Organs (text-fig. 5). 

 The two lateral organs, which are convex inwardly, have the 

 following measurements, etc. : — 



Right organ : Length 1'3 cm. Ridges 11. Sulci 12. 

 Left organ : Length l'2i cm. Ridges 12. aSWcz 13. 



The organs are situated chiefly on the sides of the tongue, but 

 the inner extremities of their laminfe and sulci extend on to 

 the dorsum. Anteriorly and posteriorly they are continued by 

 simple folds of mucous membrane. These characters are common 

 to all the Gibbons and the Chimpanzee. 



The lateral vallate papillae are level with the laminte and ridges 

 of the posterior halves of the organs, but they are not so far back 

 as in the Gorilla or Orang-Outan, and not so far forwards as in 

 the Chimpanzee and many other Gibbons. 



There are no lymphoid nodules with centx'al pits on the base of 

 the tongue. 



Thefrenum is short, and runs from the floor of the mouth to a 

 triangular depression on the inferior surface of the tongue. 



The Siamang is the only Gibbon which has no bifld triangular 

 sublingiud fold tlirough which Wharton's Ducts pass. The latter 

 open on caranculae sublinguales, as in the Orang-Outan, but it was 

 not at all clear if these were overlapped by plicae in the specimen 

 which I examined. 



In the presence of the bare area on the base of the dorsal 

 surface and in the characters of the openings of Wharton's 

 Ducts, the tongue of the Siamang agrees with that of the Orang- 

 Outan, and differs from the tongues of all the other Simiidae. 



Genus Hylobates. 

 The Slender Gibbon {H. agilis). 



I have not had the opportunity of examining the tongue of 

 R. agilis, but Flower (28) points out that it has the following 

 characters : — 



1. The tongue narrows slightly from base to apex. 



2. The apex is obtusely rounded. 



3. The vallate papillae are small, irregularly placed, and adopt 

 the Y- formation. 



4. Fungiform papillae are large and evenly distributed 



2* 



