764 DB. C. F. SONNTAG OX THE COMPARATIVE ANATOMY 



elicited by appliciitions of solutions to the centre of the oral part 

 of the dorsum diminishes as age advances. 



This atrophy of structure following loss of function may have 

 plaj^ed an important part in the reduction in and ultimate loss of 

 the primitive Mammalian tongue. 



2%e Lytla. — Two forms are to be recognised : — The lytta of 

 the tongue and tlie lytta of the sublingua. And Gegenbaur 

 showed that the latter, Avhen present, appears in one of two 

 forms. In Stenoi^s it forms a strong central supporting rod, but 

 in Tai-sms it is double. In Lemur it' is absent altogether. Owen 

 descril)ed the keel on the ventral surface of the sublingua as the 

 lytta, but sections through the tongue show a well-marked lytta 

 inside ; it is connected in the middle to the sublingua. 



Classification. 



The structures which are of value for purposes of classification 

 ai'e : — 



1. The number and arrangement of the vallate papillae. 



2. The aiTangement of the conical papillae on the oral part of 

 the dorsum. 



3. The mode in which the conical papilhe increase in size from 

 before backwards. 



4. The size of the cluster of fungiform papillte on the dorsum 

 behind the apex of the tongue. 



5. The characters of the lateral organs. 



6. The width of the ventral papillary zone, with the number, 

 characters, and arrangement of its papillae. 



7. The presence or absence and chaiucters of the lyttae of 

 tongue and sublingua. 



8. The presence or absence of the apical gland of Nuhn, and 

 the characters of the orifices of ducts and pits on the pharyngeal 

 part of the dorsum 



9. The sublingua and plicae fimbriatae. 



These features are of specific value in the case of all the 

 Simiidae, except Hylohates, and many of the Lemuroidea, but 

 they are of generic value only in all other Primates. They lend 

 additional weight to some schemes of classification I ased on 

 external and skeletal characters; in some cases they help us to 

 settle points which are not supported by a large body of A-ery 

 conclusive evidence. 



The tongue of Simia satyrus resembles that of Homo most 

 closely. Both have rounded apices, and their form and general 

 proportions are similar. They haA'e no large conical papillae on 

 the base of the tongue, and their vallate papihae form a Y. The 

 frenal lamellae are two small folds over Wharton's Ducts, and 

 their plicae fimbriatae are equally developed, but smaller thair 

 those of other Primates ; and they are the only Primates possess- 

 ing an Apical Glaaid of K"uhn. In Simia saiyrus the lateral 



