THE MAMMALIA OF THE DEEP RIVER BEDS. 69 



very distinctly marked, flattened and obliquely inclined surface for the insertion of 

 the temporal muscle ; its upper margin, however, is a thin edge, not thickened and 

 rugose as in the coyote; its lower margin forms the upper boundary of the masse- 

 teric fossa and is continuous with the prominent ridge which bounds that depression 

 anteriorly. The nearest approximation to this character of the coronoid which I 

 have been able to find among the recent Canidce occurs in C. cinereo-argentatus. The 

 masseteric fossa is large and profound, indicating a powerful muscle, which is further 

 confirmed by the character of the surface on the jugal for the origin of the masseter. 

 The condyle is somewhat flattened upon its postero-superior aspect ; it is much more 

 extended transversely than in Canis latrans, and this extension is most marked in 

 the portion external to the coronoid. 



The cranial foramina, with the exception of the foramen lacerum posterius and 

 the glenoid foramen, which have already been noticed, depart in no respect from those 

 of Canis. The mandible has a large mental foramen beneath pTs and a smaller one 

 under M, which are closer together than in the coj 7 ote ; the dental foramen occupies 

 the same position as in that species. 



III. The Brain. The cranial cast displays characters very different from those 

 of the recent Canicke, both in its general proportions and in the details of the cere- 

 bral convolutions. The hemispheres are narrow in proportion to their length and 

 taper gradually forward ; their contour is rather more alopecoid than thooid, accord- 

 ing to Huxley's distinctions. " In the Fox the contour of the brain, viewed from 

 above, is that of a pear with the narrow end forwards, laterally the contour is undu- 

 lated, presenting one slight incurvation in the region of the sylvian sulcus and 

 another in that of the supraorbital [i. e., presylvian] sulcus, while a little angulation 

 marks the junction of the olfactory lobes with the cerebral hemispheres. In Canis 

 azara? the cerebral hemispheres immediately behind the supraorbital fissure widen 

 out abruptly 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 than in C. vulpes and the brain is considerably 

 wider behind in the latter" (No. 19, pp. 215-217). In Cynodesmus, the posterior 

 widening of the alopecoid brain does not occur, but the anterior portion is more like 

 what occurs in those animals than in the thooids, though simpler than in either. The 

 hemispheres slightly overlap the lateral lobes of the cerebellum, but are notched in 

 the middle, so as to leave the vermis free. Owing to the relatively well-developed 

 tempero-sphenoidal lobes, the cerebrum has considerable vertical depth in this 

 region, but anteriorly it is very shallow as well as narrow. Apparently, the hem- 

 ispheres leave the olfactory lobes quite exposed. Except for its greater width pos- 



