OCR Text |
Show 1880.] DENTAL CHARACTERS OF THE CANIDAE. 247 rally the contour-line is undulated, presenting one slight incurvation in the region of the sylvian sulcus and another in that of the supraorbital sulcus (fig. 5, a), while a little angulation (fig. 5, b, bx) marks the junction of the olfactory lobes with the cerebral hemispheres. In Canis azaree the cerebral hemispheres immediately behind the supraorbital fissure widen out abruptly (fig. 5, a), and the lateral contour, instead of being slightly incurved at this point, presents a sharp rectangular inflection. The frontal lobe anterior to the supraorbital sulcus is much longer in C. azarce (a-b1) than in C. vulpes (a-b); and the brain is considerably wider behind in the latter. Fig. 5. Superimposed outlines of the casts of the cranial cavities oi C azarce and C. vulpes, viewed from above. The thin line belongs to the former, the thick line to the latter. a, the supraorbital sulcus ; b, the junction of the olfactory lobe with the cerebral hemisphere in C. vulpes; b,mC. azarce. Thus, notwithstanding the extremely close resemblance of these two skulls, there is a very readily discernible difference between them in the presence of frontal sinuses and the peculiar character of the anterior part of the cranial cavity in G. azarce, while both these features are absent in C. vulpes. These differences have nothing to do with size or age, inasmuch as the two skul s are almost identical in size and are both fully aduIt. Nevertheless I do not know that I should have been disposed to attach any great importance to such characters, if I bad not found, on examining a large number of canine animals, that they may be disposed in two |