96 The Suessonian Fauna in North America. (February, 
and mammals, and among the latter, of the types both of carniv- 
orous and of hoofed quadrupeds. Gayr-fishes (Lepidosteus) ap- 
pear in both countries, and the predominant mammalian genera 
of both are Coryphodon and Hyracotherium. Gigantic birds in- 
habited the land; in New Mexico they belonged to the genus 
Diatryma, and in France to Gastornis. The New Mexican ge- 
nus Ambloctonus represents the carnivorous Paleonyctis gigantea 
of the lignites of Soissons. The only marked difference be- 
tween the faunas which the then state of discovery disclosed, is 
the existence of the order Teweniodonta in New Mexico, a type 
presenting characters of the Hdentata, Rodentia, and Creodonta, 
which had not yet been found elsewhere.! 
The characters of the mammalian fauna are very peculiar, 
displaying inferiority in many respects. Thus, among the flesh- 
eaters the brain of the Oxyena is of reduced size, the hemi- 
spheres being especially small, while the olfactory lobes are very 
large and uncovered; and other Creodont genera present the 
same character. According to Gervais the genus Arctocyon, 
from the Suessonian, presents the same type of brain. The 
hoofed type, Coryphodon, shows a similar inferiority in the con- 
stitution of the brain. 
So far as these observations have gone, they coincide with 
those made eight years ago by Professor Edouard Lartet of Paris. 
He states? “that it is the result of a number of investigations 
undertaken in different horizons of the Tertiary strata, that the 
more we follow Mammalia into the antiquity of geological time, 
the greater is the reduction of the volume of the brain in com- 
parison with the size of the head and the total dimensions of the 
body. Cuvier observed the form of the brain of the Anoplothe- 
riwm in a cast of marl which was consolidated within the cavity 
of a skull of this animal, found in the gypsum of Montmartre. 
He says? ‘it has little volume, and is flattened horizontally ; the 
hemispheres do not present convolutions, but we find only a 
shallow longitudinal impression on each. All the laws of anal- 
ogy authorize us to conclude that our animal was greatly defi- 
cient in intelligence.’ In fact the skull of the Anoplotherium is 
six times as long as the cast of its cerebral hemispheres, and this 
animal, whose dimensions Cuvier compared to those of a medium- 
sized ass, had a brain smaller than that of the existing roebuck. 
1 See American Naturalist, 1876, p. 379. 
2 Comptes rendus, June, 1868. 
® Ossemens fossiles, iii., p. 44. 
