262 THE AMERICAN NATURALIST.  [VoOu. XXXII. 
the structure of its skeleton that of the creodonts, and it appears 
most probable that these primitive hoofed forms came from clawed 
types. Now Hubrecht, on embryological grounds, derives the most 
primitive of living lemurs, Tarsius, from an insectivorous-like ancestor. 
I have endeavored to prove that all lemurs must have originated 
from unguiculate types, and that the anatomical characters which the 
extinct and living lemurs have in common with the ungulates probably 
arose independently of the latter. 
It is very curious, if the mammals of the Puerco were such primi- 
tive forms, that this fauna contains so few types which led up to 
later genera. Among the generalized types of the Puerco I think we 
can designate Chriacus as such, and I believe that it may be related 
ancestrally to that curious group of pseudo-lemurs, the Hyopso- 
dontidz. Now Hyopsodus has a skull resembling very closely that 
of Adapis, although the structure of the teeth in these genera is abso- 
lutely different. What is known of the skeleton of Adapis shows that 
the proportions of the limbs are similar to what is found in Nyctice- 
bus, the anterior limbs not being elongated as in Tomitherium. 
I fail to see that any new evidence has been brought forward to 
prove that Chriacus is not a primate, or, better, an insectivore related” 
ancestrally to the Bridger pseudo-lemurs, Pelycodus and its allies. 
Surely the structure of the teeth in Chriacus is more like an early 
primate or insectivore than that of any of its contemporary creodonts 
of the Puerco. The spacing of the premolars in Chriacus is no 
objection to its being related to the primates, for among living lemurs 
we meet with forms with slight intervals in their dentition. Again, 
the large canines of Chriacus are like those of Pelycodus or Adapis, 
and the long, slender jaw may be considered a primitive primate 
character. 
In conclusion, it appears to me that the Chriacidz would find a 
more ‘congenial location” either in the Insectivora or as very primi- 
tive primates which had just emerged from the former group. If the 
Chriacide can be conveniently placed among the Insectivora and are | 
shown to be related to Pelycodus and related forms, then a decided 
advance has been made in connecting the later Eocene group of 
primitive American lemurs with those of the Puerco. 
NEW ROCHELLE, N.Y., 
January 10, 1898. 
