566 MONOGRAPHS OF NORTH AMERICAN EODBNTIA. 



the posterior root of the zygoma, there is a decided depression. Another 

 superficial depression of considerable size is situated between the orbits, just, 

 in advance of the point of greatest constriction. This point of greatest con- 

 striction lies considerably behind the middle of the skull; the width is there 

 much less than the width of the rostrum. The shape of the opening repre- 

 senting the conjoined orbital and temporal fossse is that of an inequilateral 

 triangle, with the shortest side antero-internal, the next postero-internal ; the 

 longest, Conned by the malar, being antero-external. In adults, all the sutures 

 of the top of the skull are obliterated, excepting the naso-maxillary. 



The profile view of the skull, the lower jaw being removed, exhibits the 

 remarkable flatness and approximate straightness, horizontality, and parallelism 

 of the upper and under outlines, to which the planes of the occiput, and of a 

 tangent to the incisors and ends of nasals are both perpendicular. Along the 

 top of the skull there is a slight bulge in the outline of the parietals, and 

 an equally slight depression over the orbits, whence the profile of the rostrum 

 slopes slightly downward to the end of the nasals. The occiput is perpen- 

 dicular, and appears nearly straight, though the condyles and paroccipital pro- 

 cesses project a little backward, and the end of the occipital crest curves a 

 little forward. The outline of the palate is nearly a continuous straight hori- 

 zontal line from incisors to ends of pterygoids; behind these, the bullae 

 auditorial project a little downward from the general plane. The anteorbital 

 foramen is not visible from the side, being hidden within the anterior projec- 

 tion of the zygomatic process of the maxillary. Both anterior and posterior 

 roots of the zygoma dip nearly or quite down to the level of the palate; in 

 its continuity, the malar rises with a gentle arch. 



Seen from below, the skull presents, of course, substantially the same 

 contour as from above ; so we may at once proceed to notice the details. 

 It is only in this one of the three views here described that the anteorbital 

 foramina appear. These are small, simple, oval apertures not prolonged into 

 canals, circumscribed by the two roots of the zygomatic process of the max- 

 illary ; they are oblique to all three coordinate planes of the skull, their long 

 axes being directed upward, forward, and outward. Notwithstanding their 

 small size and seemingly inconvenient position, they transmit, as usual, along 

 with the nerve, a little fascicle of the masseter muscle. The incisive fora- 

 mina, of moderate length, but narrow, reach nearly or quite to the maxilla- 

 ries, but their sides are entirely bounded by the inter maxilla lies. The septum 



