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; i. 



566 



MONO0RAPH8 OF NOUTH AMERICAN ItODKNTIA. 



tlin posterior root of tlin zy^ornn, tlieru in n (l(!ciHcil tlnproxsioii. Another 

 superiiciiil depression of considoraltle size is silu( led hctwcen the orhits, just 

 in ailvane<! of the point of greutost conslriclion. This iwtiiit of greatest con- 

 strielion lies considerably licliind the nii(hlle of the skull; the width is there 

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

 senting the (;onjoined oriiital and temporal fos^e is that of tin ino(piilateral 

 triangle, with tho shortcsl side an<ero-internal, the next postero-inlernal ; the 

 longest, formed hy the malar, being antero-cxternal. In adults, all the sutures 

 of the top of the skull arc obliterated, excepting he naso-mnxillary. 



The profde 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 n 

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

 top of the skull there is n slight bulge in the outline of the i>arietal8, and 

 an equally slight depression over the orbits, whepce (he 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 buUse 

 ouditoriER project a little downward from the general plane. The antcorbital 

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

 tion of the zygomotic 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 anteorbitol 

 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 

 wilh 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 intermaxillaries. The septum 



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