408 Wortman — Studies of Eocene Mammalia in the 



resembles that of Tarsius very closely, and the premolars in 

 the Bridger species at least are reduced to two ; there is no 

 lemurine modification of the incisors or first lower premolar ; 

 the brain is relatively large, and the face is considerably bent 

 down on the basicranial axis, as in Tarsius / while, lastly, the 

 species are small and the orbital cavities enlarged. 



From this striking array of similarities which Cope was care- 

 ful to point out, I am fully convinced that the two forms are 

 closely related and should be placed in the same group. 

 In like manner, we may feel reasonably certain in arranging 

 the extinct European Necrolemnr of Filhol in the same group. 

 Although the skull characters are less perfectly known than in 

 the American species, yet the lachrymal region, the dentition, 

 and the general appearance of the single skull known, all 

 betray the same fundamental resemblances to Tarsius noted 

 in Anaptomorphus or Euryacodon. I do not hesitate, there- 

 fore, to classify it with this series. The same may also be true 

 of the imperfectly known Microchoerus of the European Eocene, 

 but this is not at all certain. There is some evidence that the 

 latter genus is closely related to and represents Hyopsodus in 

 Europe. 



The position of the remaining American genera, Omomys, 

 Hemiacodon, and Washakius, is more problematical. No com- 

 plete skull of any of these forms is known, and it is impossible to 

 say whether they most resemble Tarsius or the monkeys. In one 

 species, llemiacodon gracilis, a fragment of the maxillary is suffi- 

 ciently preserved to show that there was no union between the 

 malar and lachrymal. The incisors do not display any lemurine 

 characteristic and the inference is tolerably clear that they belong 

 either with the Paleopithecini or with the true monkeys. I may 

 add just here that there is such a marked resemblance between 

 the teeth of Omomys and those of certain of the living South 

 American Cebidse, that I am strongly inclined to the belief that 

 these extinct forms are true monkeys. 



There yet remains to be discussed another group of extinct 

 Primates whose remains are better preserved, and hence more 

 completely known, than any others yet discovered in the Eocene, 

 the Adapidse of Europe and the so-called JSTotharctidse of 

 America. Cope* arranged them in the group Mesodonta, 

 which he made a suborder of his order Bunotheria. He in- 

 cluded in the Bunotheria the suborders Creodonta, Mesodonta, 

 Insectivora, Tillodontia, and Tseniodonta, at the same time hold- 

 ing that the Prosimise, or Lemuroidea, should be placed here as 

 well. He seems to have entertained the opinion that all were 

 ordinally distinct from the Quadrumana, or Primates, although 



* Tertiary Vertebrata, 1884. 



