368 . NOTES ON the canidce of the white river oligocene. 



II. The Skull (PL XIX, Figs. 11, 12). 



The skull of Cynodictis is decidedly primitive and in general appearance resembles 

 that of such viverrine genera as Paradoxurus, rather than that of the modern Canidce. 

 Among the latter the alopecoid series have skulls more resembling the type of Cynodictis 

 than do the thooids, though the Brazilian bush-dog {Icticyon) is, on the whole, most like 

 the fossil in the proportions of its skull. 



In Cynodictis, as in Daphcenus, the facial or preorbital region of the skull is very 

 short and the cranial portion very long. The occiput is low and the upper contour of 

 the skull rises steeply from the inion to about the middle of the parietals, whence it 

 descends in an almost straight line to the anterior nares, the only departure from straight- 

 ness being a hardly noticeable concavity or " dishing " of the nasals about midway in 

 their length. In Vulpes the profile is cpiite similar, but the posterior rise from the occi- 

 put is much shorter and less steep, and the dishing of the nasals is more conspicuous. 

 The sagittal crest is low and weak, and in the John Day C. lemur, the smallest sjtecies 

 of the genus, the crest is replaced by a lyrate sagittal area. The cranium, though slen- 

 der, elongate and contracting anteriorly, is relatively fuller and more capacious than in 

 Daphamtis, and the postorbital constriction, though much deeper, is as near the orbit as 

 in the modern foxes, and is, therefore, much farther forward than in Daphcenus. The 

 John Day specimens, which Cope has referred to C. gregarius ('85, PL LXVIII, Fig. 6), 

 have an even fuller cranium and shallower postorbital constriction, which should, per- 

 haps, be a reason for separating these animals specifically from the White River forms. 

 The muzzle in Cynodictis is very slender, but tapers gradually and is not so abruptly 

 constricted at the line of the infraorbital foramina as in Daphcenus. In the European 

 representatives of the genus the skull is much like that of the American species, but is 

 somewhat more primitive and like that of Daphcenus. Thus, the muzzle is more abruptly 

 constricted, and the postorbital constriction is deeper and occupies a more posterior posi- 

 tion. 



A more detailed examination of the skull brings out the following facts : 



The occiput is low, yery broad at the base and narrowing toward the summit less 

 than in the large wolves, but more than in Vulpes or Urocyon ; a well-marked median 

 convexity is produced by the vermis of the cerebellum.- The crest of the inion is low 

 and weak, much less prominent than in Daphcenus. The foramen magnum differs some- 

 what in shape in the different individuals, being in some low and broad, and in others 

 of subcircular outline, a difference which may. in part, be due to a slight crushing. The 

 dorsal margin of the foramen projects much more- prominently than in the recent Canidce. 



The basioccipital is long, broad and of nearly uniform width throughout ; it is 



