No. 2007. DESCRIPTION OF ME80PL0D0N MI RUM— TRUE. 655 



Inferior aspect. — Wings of the basisphenoid veiy thick. Posterior 

 end of vomer terminating in an irregular angular projection, notched 

 in the median line. Lateral portion of the pterygoids very wide; 

 median portion narrow with the external borders concave and the 

 inferior surface convex and devoid of the oblique ridge seen in M. 

 europxiis; the anterior convex extremity broad. Palatines almost 

 concealed anteriorly by the pterygoids, but appearing on the median 

 side of the latter as a narrow triangular area with the apex directed 

 backward. External to the pterygoids the palatines occupy an elon- 

 gated pyriform area, as in M. europseus. 



The maxillaries extend backward along the median line so far that 

 they prevent the palatines from meeting as they do in M. europseus. 

 Only a very small area of the vomer is visible between the closely 

 approximated pterygoids. Anterior expanded end of malar bone 

 large and nearly as broad as long. It extends into and occupies the 

 base of the anteorbital notch. Lachiymal with a broad truncated free 

 margin; irregularly strap-shaped proximally and overlapped by a 

 broad posterior extension of the maxillary bone. Its anterior free 

 margin forms the outer half of the external boundary of the ante- 

 orbital notch. 



Beak slightly and evenly convex at the base. The vomer appears 

 as an elongated, fusiform ridge in the middle of the beak, the length 

 of the visible portion more than one-third the length of the beak. 

 Anterior to it the premaxillse are convex along the median line and 

 concave on either side, thus forming two long, moderately deep 

 grooves. At the apex of the jaw the premaxillas diverge from the 

 median line and are not in contact. 



MANDIBLE. 



Plate 57, fig. 1. 



The mandible is thick and heavy. Viewed from the side, the infe- 

 rior border is concave at the middle and convex at either end. The 

 symphysis is strongly bent upward. The angle is broad and rounded 

 and projects backward much beyond the condyle. The coronoid 

 process is very obtuse and is not separated from the condyle by an 

 emargination. Anterior to it the superior border of the ramus is very 

 convex, while it is concave opposite the posterior end of the sym- 

 physis. 



The symphysis occupies one-fourth the length of the jaw. The 

 upper surface is flat, but the two halves are inclined toward the 

 median line. It is rounded anteriorly. 



TEETH. 



Plate 57, fig. 2. 



The two mandibular teeth are remarkable for their small size, ante- 

 rior position, and strong forward incliny-tion. They were entirely 



