108 



GREGORY : 



NOTHARCTUS, AN AMERICAN EOCENE PRIMATE 



The vertebrae were worked out and restored by Mr. Albert Thomson, who used the vertebral column 

 of Lemur mongoz as a model in restoring the missing parts. While further study has revealed many 

 minor characters in which the vertebrae of Notharctus differ from those of Lemur, yet, in the main, that 

 is tlie nearest available pattern. 



The parts represented either by fragments or by more or less complete vertebrfc are indicated in 

 the following table. 



Vertebrae Represented 





TV. oshornt 

 No. 11474 



A^. oshoTui 

 No. 11473 



. / IjTQ Yt 71 11 -S 



No. 11478 





A^. oshoTfii 

 No. 11474 



A^, oshwTii 

 No. 11473 



A'', ty 

 No. 1 



C 1 



+ 



0 



+ 



L 7 



+ 



0 



+ 



C 2 



0 



0 



+ 



LS 



0 



0 



0 



C 3 



+ 



0 





S 1 



+ 



0 



+ 



C4 



+ 



0 





S2 



0 



0 



+ 



C 5 



+ 



0 





S 3 



+ 



0 



+ 



C 6 



0 



0 



0 



(•<! 1 



{•f)+ 



0 



+ 



C 7 



0 



0 



(1 



C.l 2 



vn+ 



0 



0 



D 1 



+ 



0 



0 



( ■<! 3 



rn+ 



0 



(?)+ 



D 2 



+ 



0 



0 



C.l 4 



(?)+ 



0 



0 



D,3 



+ 



0 





( '.i r. 



0 



0 . 



('0+ 



D4 



+ . 



0 





Cd (1 



0 



0 



0 



D 5 





0 





c.l 7 



+ 



0 



0 



D () 



+ 



0 





( '(I N 



0 



0 



0 



D 7 



+ 



0 



{•!) + 



(•(1 9 



0 



0 



(?)+ 



D 8 



+ 



0 



(■/) + 



(VI 10 



cn+ 



0 



(?)+ 



D fl 





+ 





Cd 11 



0 



0 



(?)+ 



1) 10 





+ 





Cd 12 



(?)+ 



0 



(?)+ 



1) 11 



0 



0 





Cd 13 



(?)+ 



0 



(?)+ 



?1) 12 



0 



+ 





Cd 14 



(?)+ 



0 



(?)+ 



L 1 



0 



+ 



0 



Cd 15 



{-n+ 



0 



(?)+ 



L2 



+ 



0 



+ 



Cd 1() 



(?)+ 



0 



(?)+ 



L3 



+ 



0 



+ 



Cd 17 



(?)+ 



0 



(?)+ 



L4 



+ 



0 



+ 



Cd i.s 



0 



0 



(?)+ 



L5 



+ 



0 



+ 



Cd U)-2S ( 



) 0 



0 



0 



L 6 



+ 



0 



+ 











It is probable that the \-ertebral formula of Notharctus was very nearly, or actually, the same as that 

 of Le^nur, and that it may be written as follows: 

 C 7, D 12, L 8, S 3, and Cd ? 

 In Lemur mongoz it is: 



C 7, D 12, L 6-8, S 3, Cd. 28. 

 In Lemur varius it is: 



C 7, D 13, L 6, S 2-3, and Cd 27-29. 

 Thus, in the genus Lemur generally the lumbar vertebrae are 6 or 7, rarely 8, and the sacrals are usu- 

 ally 3, rarely 2. 



The vertebral column in general approaches that of Lemur mongoz in the proportions of the cervi- 

 cals, dorsals and lumbars; but the coccygeal vertebrae are considerably lighter and the tail much more 

 slender. 



The column is distinguished from that of the Cebida?, as typified by Cehm, in having the dorsal 



