599.8 309 



II. 



The Lemurs as Ancestors of the Apes. 



'"THE question whether the lemurs are the ancestors of the apes 

 1 needs to be discussed again, as the result of the recent investi- 

 gations of Hubrecht (i) and Leche (2) on the Tarsier {Tarsius) of the 

 Indo-Malayan Archipelago. This little squirrel-like animal, as is 

 well-known, has long been placed in zoological works in a rather 

 isolated position among the lemurs, on account of its anomalous 

 characters. Hubrecht now finds, from the study of the placental 

 connection between the embryo and the parent, that this strange 

 genus can no longer be regarded as a lemur, but must be placed 

 among the apes in the higher division of the Primates. Leche, on the 

 other hand, from a study of its teeth, considers that it is a lemur 

 beyond all doubt. 



I propose, therefore, as briefly as possible, to discuss the charac- 

 ters of the skeleton of Tarsius, to determine whether or not this 

 existing genus can be considered as a synthetic type connecting the 

 lemurs with the apes, and whether it truly shows that the two sub- 

 orders of the Primates, as commonly understood, are derived from 

 one and the same ancestral stock. The animal is, indeed, one of 

 those generalised forms, preserving in its skeleton many characters 

 found in its primitive ancestors of the Eocene period, as shown by an 

 examination of the skull and teeth. 



The skull of Tarsius very closely resembles that of Anaptomorphus 

 from the North American Eocene, and of Microchoerus from the French 

 Lower Tertiary Phosphorites. All these animals have a rather short 

 and broad head, with much enlarged orbits, and huge auditory bullae. 

 In the skull of the two extinct genera, however, the rim of the orbit 

 is incomplete below, while in Tarsius it is nearly closed here by a 

 well-marked lamina of bone extending from the aHsphenoid to the 

 malar. The latter feature has not been observed in any other lemu- 

 roid, and more closely associates Tarsius with the apes. 



The teeth of this afiimal are of a very primitive type, which is 

 common in the lowermost Eocene strata. Like nearly all the Mam- 

 malia of the North American Puerco Formation (lowermost Eocene), 

 it exhibits only three tubercles on the crown of its back teeth in the 



