OF THE TONGUES OF THE MAMMALIA. 7 



there are more than one point the body may be cylindrical, or 

 flat and thin (text-fig. 2 A, a-g). The cylindrical types are 

 interspersed among the others. They have a granular surface, 

 and some of them are very rough. In the latter case, however, 

 it is difficult to be precise as to their character ; they may have 

 lost long points as the result of handling (text-fig. 2 A, h, i). 



The relative proportions of the filiform and cylindrical types 

 differ in different tongues. Either type may be in excess, and 

 they may in some cases be evenly distributed, but it is usual to 

 find one form predominating. 



The different forms are shown highly magnified in text- 

 fig. 2 A, nos. a-l. 



Lymphoid Tissue. 



The base of the tongue contains much lymphoid tissue which 

 gives the surface a lobulated appearance, and there is a great 

 contrast between it and the rough anterior surface, when the 

 tongue is viewed from the side (text-fig. 1 B). The degree of 

 contrast depends greatly on the number of filiform papilla? on 

 the anterior two-thirds of the dorsum ; when these are very 

 numerous the roughness is greater and the contrast more marked. 



The lymphoid nodules vary in size, and the large ones have 

 small central pits, but it is only possible to tell by microscopic 

 examination whether any one orifice has ducts of glands con- 

 nected to it or not. Few of the pitted follicles lie anterior to 

 the most posterior vallate papilla. 



The Lateral Organs (text-figs. 1 B, g, & 2, AA'). 

 Boulart and Pilliet [2] have stated that the lateral organs of 

 the Anthropoid Apes are well developed, and mention that the 

 Chimpanzee has twelve ridges in its organs, but they do not say 

 whether both organs have the same number of fissures and 

 ridges. Dwight (123) showed that each organ is convex in- 

 ternally. I agree with Dwight, but not with Boulart and 

 Pilliet. All my specimens have organs convex inwardly, but 

 there is great variability in the number of fissures and ridges 

 as the following figures show : — 



Specimen 1 (text-fig. 2, AA'). 



Right organ : Length 1-55 cm. Ridges 15. Sulci 16. 

 Left organ : Length T6 cm. Ridges lb Sidci 15. 



Specimen 2. 



Right organ : Length 1"4 cm. Ridges 7. Sulci 8. 

 Left organ : Length L7 cm. Ridges 9. Sulci 10. 



Specimen 3. 



Right organ: Ridges 10. Sulci 11. 



Left organ: Ridges 9. Sulci 10. 



Each organ begins anteriorly as a number of sulci on the 

 infero-lateral aspect of the tongue, but the pieces of the tongue 



