:M E G A L O N Y X . 1 1 



.surfoce, four inches in width at the posterior margins of the first moLars, and two 

 inches and a third at its anterior border. It is everywhere perforated by large 

 vasculo-neural foramina, which communicate with a palatine canal piercing the hard 

 palate on each side antero-posteriorly. The anterior extremity of the hard palate, 

 between the position of the first molars, presents a large, oval, incisive foramen, which 

 measures one inch and a half in the median line, and fourteen lines transversely. 

 In front the incisive foramen is closed by the intermaxillary bones, which, in the 

 present specimen, are separated by a narrow fissure, but are co-ossified with the 

 maxillary bones. 



The alveoli for the posterior four molars extend to more than half tlie depth of 

 the face, and are nearly vertical in their direction except the last one, which curves 

 backward and downward. The outer margin of their orifices is half an inch 

 above the median convexity of the hard palate; and between this convexity and 

 the exserted portion of the contiguous teeth, a deep gutter exists. The extent of 

 the tract occupied by the posterior four molar alveoli is a little over three inches 

 antero-posteriorly, and fourteen lines transversely. 



From the first molars the others are separated by a hiatus, which presents a 

 concave border outwai'dly, and in a straight line measures two inches. 



Corresponding with an unusual degree of development of the first molai', its 

 alveolus is large and deep ; and it commences within the position of the upper part 

 of the anterior orbital margin. In its course to the antero-inferior angle of the face 

 it curves forward, downward, and very slightly outward. The long diameter of its 

 orifice is directed forward and inward, and measures twenty lines. 



Posterior Vieio. — (PL VI, Fig. 3.) The occipital surface in outline has the same 

 form as in MijJodon, but is relatively deeper in comparison with its bi'eadth. The 

 upper and lateral margins of the inion form a semicircle, and are roughened for 

 muscular attachment. 



The occipital condyles are nearer together, and are separated above by a deeper 

 notch than in Mylodon. Their greatest distance from each other at the middle, is 

 about two inches. 



The occipital foramen is circular and is sixteen lines in diameter. 



The median portion of the occiput is elevated into a narrow vertical crest which 

 ceases near the occipital foramen. Upon each side the surface is rugged; and it pre- 

 sents about an inch below the summit of the inion a transverse crest, which at 

 its outer part forms an irregular tubei-osity. 



Anterior View. — (PI. VI, Fig. 2.) The end of the f\xce is relatively narrower 

 and higher than in Mi/lodon ; and in outline is more vertically oblong qnadrihxteral, 

 with the upper margin convex and the sides nearly vertical. 



The orifice of the nose is irregularly circular, and is a little more than three 

 inches in diameter. Inferiorly it is bounded by a broad sloping surfixce, formed by 

 the. antero-inferior portions of the alveoli for the first molars and the intervening 

 intermaxillary bones. 



The latter are simple, oljlong, quadrilateral plates, a little more than two inches 

 in depth, and three quarters of an inch in breadth. 



