402 Wortman — Studies of Eocene Mammalia in the 



movement of the lower jaw, as in the Rodentia. The ento- 

 carotid circulation in Cheiromys is like that of the lemurs ; 

 the lachrymals are large, with extraorbital extension, and the 

 external opening of the lachrymal canal is outside of the orbit. 

 As in the lemurs, the lachrymal and malar are in contact. 

 Cheiromys also agrees with the lemurs in having the fourth 

 digit of the.manus the longest of the series, and, except for the 

 hallux, the terminal phalanges are clawlike. In all, there is a 

 well-ossified tympanic bulla, and the limbs and feet are elongate 

 and fully adapted to arboreal life. 



Owing to. the wide separation- both in time and space, it has 

 been doubted whether there is any genetic, connection between 

 the aberrant Madagascar species and the extinct North Amer- 

 can forms. Indeed, Osborn has recently placed the American 

 series in a primitive suborder of the Rodentia, which he calls 

 the Proglires. After a careful investigation of the evidence, 

 I do not hesitate to state it as mj belief that the Madagascar 

 and American forms are intimately related. There can be no 

 two opinions respecting the Primate affinities of Cheiromys. 

 This has long since been settled beyond all dispute, and 

 although but comparatively little of the skeleton of the 

 American species is known, what is known betrays the 

 same Primate stamp with equal distinctness. In the New 

 World forms, we have the following conditions presented: 

 Ancient primitive Primates undergoing a rodent-like modi- 

 fication of the central pair of incisors, together with the 

 disappearance of the outer pair and the Canines. In Ameri- 

 can genera, the process is 'progressive but incomplete, while 

 in the living Madagascar species the modification is com- 

 plete. No stronger general argument, it seems to me, could 

 be put forth in favor of their relationship, especially when it 

 is remembered that these are the only representatives of the 

 Primates in which the slightest tendency toward such modifi- 

 cation is shown. That so distinctive and profound a change 

 could have originated twice independently, in the same 

 order, is so highly improbable as to be unworthy of serious 

 consideration. That the group is of pre-Tertiary origin is 

 shown by the fact that Mixodectes, its oldest representative, is 

 already highly modified in the Torrejon or second stage of the 

 Lower Eocene. I propose for the suborder the slightly modi- 

 fied term Cheiromyoidea. 



The second suborder of the Primates includes the lemurs, a 

 group which has long been recognized by-zoologists as consti- 

 tuting a primary division of the order. Some authorities are 

 inclined to deny the genetic connection of this group, as well 

 as that of the Cheiromyoidea, with the true monkeys, and 

 assign to them a separate and independent ordinal rank. This, 



