14 BULLETIN 73, UNITED STATES NATIONAL MUSEUM. 



considerable portion of the premaxillas. The convex inferior outHne of the l)eak 

 and its great depth at the base are also salient peculiarities. 



Ventral aspect (PI. 5, figs. 1, 2).— The anterior ends of the palatine bones are 

 bifurcated, the inner part being the smaller. The two bones make Init a narrow 

 ano-le with the median line, instead of a wide one, as in hidens, and the surface of the 

 maxilla3 between them is strongly convex instead of fiat . This convexity is narrowed 

 at both ends, or, in other words, is fusiform in shape. No similar conformation is 

 found in hidens, in which the inferior basal area of the maxillfe is flat. 



In the young Atlantic City skull of europxus, the vomer is visible as a small, 

 narrow, club-shaped piece, 68 mm. long. Anteriorly it joins the premaxillse, which 

 form a prominent ridge in the median line. On each side of this ridge is a wide 

 and quite deep groove. As the beak is lacking in the adult North Long Branch 

 skull, its peculiarities can not be made known. In the type-skull the form is the 

 same as in the Atlantic City skull, but the vomer does not appear at all on the 

 palate. In bidens the shape of the inferior surface of the premaxillffi at the distal 

 end is quite difl'crent. A very narrow groove runs parallel with and close to the 

 median line and the whole surface external to it is more or less convex. 



MANDIBLE. 



The mandible of the Atlantic City specimen of M. europseus resembles that of 

 the type, as figured by Van Beneden and Gervais, in the shortness of the symphysis 

 and in the position of the tooth, which is in advance of the posterior end of the 

 symphysis. A number of differences, however, require consideration. (PI. 11, 

 figs. 3 and 6.) 



In the type, the symphysis, as shown by Van Beneden and Gervais' figure, 

 plate 24, fig. 2a, is a little more than one-fifth the length of the mandible. The 

 same relative proportion is found in the Atlantic City specimen, but, as the latter 

 is a younger individual, one would expect the symphysis to be shorter. The figure 

 of Van Beneden and Gervais gives the impression that in the type the end of the 

 mandible is broken, and that, hence, the symphysis is shorter than it was originally. 

 It will be observed that figures 2 and 2a do not agree as regards the length between 

 the tooth and the end of the jaw, figure 2a showing a greater length. In figure 2, 

 however, the jaw seems rather too long for the cranium, and if the greater length 

 of the symphysis shown in figure 2a were introduced, it would certainly be so. The 

 explanation of this discrepancy is not readily found; but one may be allowed to 

 think that the symphysis is not so blunt in the type as is shown in figure 2. , 



In the Atlantic City specimen the superior lateral free margin of the symphysis 

 is straight, wliile in the type it is much elevated. This is no doubt due to differ- 

 ence in age and possil:>ly in sex. The type shows three or four mental foramina, 

 while the Atlantic City specimen has one large posterior one and seven smaller 

 ones anterior to it. 



Another peculiarity of the latter specimen is that the coronoid process is 

 situated much in advance of the condyle, while the angle extends considerably 

 behind it. In the type both are nearly in line with the cond\de. I am unable to 

 explain this difference. 



