ENDOCRANIAL ANATOMY OF FOSSIL MAMMALS 361 
similar to its condition in Hoplophoneus (?) (fig. 9) in that it 
lies so far removed from the median line. An indefinite lateral 
projection doubtless indicates a lobulus petrosus, but of its form 
and structure nothing can be told. The size of the cerebellum 
as compared to the cerebrum is much larger in Daphaenus than 
in Aenocyon. 
Aenocyon (Canis) dirus Leidy. The giant wolf (Aenocyon 
dirus Leidy), found so abundantly in the asphalt deposits of 
southern California, was and is the largest representative of its 
kind. The skeletal remains of this form are very abundant in 
the Rancho la Brea beds and every detail of its skeletal organi- 
zation has been discussed by Merriam (712). The skull is un- 
usually large and the brain-case capacious, the inner table of 
which is strongly marked by the gyri and sulci and by the menin- 
geal vessels (figs. 13, 14, and 15). The artificial cast from which 
these figures were made was reproduced from a single practically 
complete brain-case of this wolf, given the writer by Mr. E. 8. 
Riggs. The brain-case was carefully sawn, longitudinally, and 
the hard-packed asphalt matrix removed until the inner surface 
was clean. In this process the delicate osseous tentorilum was 
partially destroyed. It would be important to have a series of 
casts of the endocranial cavities of various individuals of this 
wolf—a task readily accomplished by those having access to a 
number of perfect skulls. I have contented myself with a study 
of this single cast. A series of such casts of the brain of this 
wolf has been made by Dr. J. C. Merriam, and a discussion of 
them will be included in his Rancho la Brea studies. The 
robust brain of this giant wolf may be readily compared with 
the modern dog. A comparison was made with an endocranial 
cast from the skull of a large bulldog, the most obvious differ- 
ences being the more sharply marked sulci in the extinct form. 
If complexity of cerebral pattern is any indication of intelligence, 
then the Pleistocene wolf was a very intelligent creature. The 
increase in complexity shown by this wolf (figs. 18, 14 and 15) 
will be more striking if one compares it with the simple pattern 
of its Oligocene forebear, Daphaenus (fig. 12). 
