28 Wortman — Studies of Eocene Mammalia in the 



there are nine teeth in the lower jaw, which with little doubt 

 are to be interpreted as two incisors, one canine, three premo- 

 lars, and three molars. In another series which includes Anap- 

 tomorphus, Washalcius, JVecrolemur, and presumably Mioro- 

 choerus, there are only eight teeth in the lower jaw, as in 

 Tarsius. In this latter genus, the missing , tooth is known to 

 be an incisor, and it is almost equally certain that in Anapto- 

 morphus it is a premolar. In Neerolemur, although perfect 

 lower jaws bearing the full inferior dentition are known, it is 

 quite impossible correctly to assign the teeth in the front of 

 the jaw to their proper categories. In the case of Washahius, 

 if the total number of teeth is correctly determined to be eight 

 in each lower jaw, then it is reasonably certain that the missing 

 tooth is an incisor, as in Tarsius. Just what significance is to 

 be attached to those differences can not now be properly esti- 

 mated, but if among the living Lemuroidea the presence or 

 absence of one tooth does not indicate more than a subfamily 

 distinction, I fail to see why such a character should be 

 regarded as of greater importance among the extinct forms. 

 It has been customary with some authors to associate Miero- 

 chcerus and Neerolemur in a separate family, and remove them 

 from the American species, on account of the complexity and 

 more advanced character of their teeth. It has, in fact, been 

 insisted upon by Leche* that they belong to the Lemuroidea. 

 If, however, the carotid circulation is like that of Tarsius, they, 

 with the American forms, probably belong in the Paleopithe- 

 cini ; and the complexity of their teeth will no more entitle 

 them to distinct family rank than that of the Indrisinse would 

 cause them to be classified as a separate family of the Lemu- 

 roidea. The differences in tooth structure between Neerolemur 

 and Hemiacodon are not as great as they are between Propi- 

 theeus and Lemur. ,f I therefore provisionally arrange these 

 extinct forms in a single family Anaptomorphidse, with at least 

 two well-marked subfamily divisions. There can be no doubt 

 apparently that Tarsius, by reason of the modification of its 

 hind limbs and because of other modernized features, should 

 be placed in a distinct family. 



* Untersuchungen ueber das Zahnsystem lebender und fossiler Halbaffen. 

 Festschrift fur Carl Gegenbaur, Leipzig, 1896. 



f That Neerolemur and Microchoerus exhibit some striking resemblances 

 to the Indrisinae among the Lemuroidea, however, is certain, and it may well 

 be that in these forms we have the ancestors of this group of lemurs and a 

 true transition from the more or less upright position of the lower incisors 

 to that of the procumbent implantation. 



