742 DK. C. F. SONNTAG ON THE COMPARATIVE ANATOMY 



Crests are present on the ventral surface in all species. They 

 are three in number in the Indrisidse and Lemuridfe, except 

 Microcehus, but only one is present in the Lorisidse, Galagidse, 

 Microaehus, Ghiromys, and Tarsius. The dorsal surface bears a 

 crest of variable size in the Lorisidae and Galagidge, the most 

 pronounced one occurring in Pe7-odicticus potto. 



The consistence varies greatly. In all the Lemuroidea the 

 snblingua is horny, but in Tarsius it is soft. In the Lemnridee 

 and Indrisidaj the entire sublingua is uniformly thick, but in the 

 Lorisid*, Galagidse, and Chiromys the central parts are thicker 

 and harder than the lateral parts. The horny covering is pro- 

 duced bv an excessive thickening of the stratum corneum. 



In Lemur the sublingua can be separated to a considerable 

 extent from the under surface of the tongue, but in Tarsius they 

 cannot be separated, for the sublingua is demarcated from the 

 tonoue by a slight groove only. In the Lorisidse and Galagidse 

 the degree of mobility is intermediate, and in Chiromys it is 

 greater than that described in the writings of Gegenbaur (5) and 

 Pocock(15). 



I have already summarised the differences between the sub- 

 linguse of the Prosimiae and Marsupialia (20). 



Flower (4) and Pocock (15) believe that the function of the 

 sublingua is to clean tlie posterior surfaces of the incisor teeth ; 

 but others think it has no function, and regard it purely from 

 the point of view of phylogeny. I believe that the sublingua of 

 the Marsupialia is entirely a vestigial structure. 



The Lytta. 



The tongues of the Lemuroidea and Tarsioidea have lyttse 

 which are of two kinds: — 1. The lytta of the tongue. 2. The 

 lytta of the sublingua. 



The lytta of the sublingua is absent in Lemiir, double in 

 Tarsius, and single in Perodicticus and Loi^is ; in all these forms 

 it is internal, but in Chiromys it forms a strong, external, 

 nodulated ridge ending anteriorly in a hook. 



The lytta of the tongue is present in Perodicticus, Loris, and 

 Chiro?nys, but Gegenbaur and Owen missed it in the latter. It 

 is connected to the lytta of the sublingua by connective tissue. 



I have nothing to add to existing accounts of the histology of 

 the sublingua and lytta. 



Family L E M u R id ie. 

 Genus Lemur. 



In all species the apex is rounded and covered with small 

 conical and fungiform papillae, but has no notch. The lateral 

 borders increase in thickness from before backwards and have 

 lateral organs at their posterior extremities. The oral part of the 

 dorsum possesses several wide, shallow transverse ridges and 

 sulci, and there is a smooth, non-papillary area in front of the 



