FARLY ONTOGENETIC PHENOMENA IN MAMMALS. 161 
cussed on p. 115, can hardly be called a placenta at all, corre- 
sponds with the villiferous diplotrophoblast, with massive vill 
of Nycticebus in all respects, and I have no doubt but that also 
the relation between diplotrophoblast and allantois, etc., in 
Chiromys will be of the same type as that of Nycticebus (Fig. 
148), so that really nothing is in the way of following Wort- 
man’s suggestion and placing these two suborders of Chiro- 
myoidea and Lemuridea together, selecting for the order which 
comprises them the name of Lemures as above stated. Besides 
the recent Chiromys madagascariensis, Wortman adds 
the fossil genera Mixodectes, Cynodontomys, Microsyops 
Smilodectes, and Metachiromys, in all of which the dentition 
has acquired that peculiar Rodent-like aspect which is so 
characteristic for the recent genus. I prefer Wortman’s views 
to the proposal which Osborn has made, viz. to unite the six 
American fossil genera into asuborder of the Rodentia, which 
Osborn calls the Proglires. _Wortman states that what is 
known of the skeleton betrays the same Primate stamp with 
equal distinctness, as does the skeleton of Chiromys. And 
as to the modification of the incisors which is complete in the 
living Madagascar species, it is progressive but incomplete in 
she American genera. Wortman adds that “these are the 
only representatives of the Primates in which the slightest 
tendency towards such modification is shown. That so dis- 
tinctive and profound a change could have originated twice 
independently in the same order is so highly improbable as 
to be unworthy of serious consideration.” The group is of 
preetertiary origin, Mixodectes, its oldest representative being 
already highly modified in the second stage of the lower 
Kocene. 
The Lemuroidea, which may be united with the Chiro- 
myoidea into the order of Lemures are characterised by 
Wortman in the following manner : 
“Limbs elongate, prehensile, and adapted to an arboreal 
habit ; incisors of lower jaw reduced in size, pectinate and 
proclivous in position ; anterior lower premolar very gener- 
ally enlarged and functioning as a canine; ento-carotid canal 
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