PROFESSOR OWEN ON THE MEGATHERIUM. 
575 
that the Megatherium was a beast of less intelligence, and with the command of fewer 
resources, or less varied instincts, than the Elephant. 
The ‘ maxilla superior,’ or maxillary bone, may be divided into a palatal, alveolar, 
and facial portion: the latter (Plate XXI. fig. 1, 21 ) is remarkable for the excess 
of its vertical over its antero-posterior extent : it forms, with the coalesced lacry- 
mal (/), the anterior and part of the inferior boundary of the orbit by a strong sub- 
vertical outstanding plate, curved with the convexity forward, perforated at the 
middle part of its base by the antorbital canal (r), which is double on the left side, and 
near the upper part of its thick obtuse margin by the lacrymal canal (/) : it is smooth 
behind, or next the orbit, rather rough and irregular in front: a rough, shallow de- 
pression (Plate XXIII. fig. 2, s) near the upper part of this surface indicates the origin 
of a strong labial muscle. The outer surface of the facial plate of the maxillary is 
smooth and slightly undulated ; it evidently extends as far as the postorbital process 
upwards and backwards, in connexion with the nasal bone : its anterior border 
(Plate XXL fig. 1, n), terminating the side of the nostril, is vertical, slightly concave 
and sharp, and is smoothly excavated on the inner side or towards the nasal cavity. 
The lower part of this nasal wall presents a deep and rough sutural notch for articu- 
lation with the premaxillary bone. 
The alveolar part of the maxillaiy (Plate XXIV. i, v) extends about an inch below 
the suborbital process. The extent of the alveolar tract is 10 inches; its greatest 
breadth is 2 inches 4 lines, viz. between the second and third teeth. The number of 
alveoli is five. The first (i) has a subtriangular transverse section, with the apex very 
obtusely rounded off and turned forward ; the borders of this alveolus are sharp and 
somewhat produced below the level of the surrounding bone. The second alveolus {ii) 
is close to the first, and the corresponding teeth are nearly in contact ; its transverse 
section is quadrate, the hinder side being the broadest, the outer side the narrowest; 
the fore-side is more curved than the back one. The partition between this and the 
third alveolus is thicker than the preceding one, and the teeth stand further apart. 
The third and fourth sockets are most nearly of a square form, but the transverse 
diameter predominates ; the fifth socket (v) is suddenly reduced in size, and re- 
sembles most the first in form, but with the rounded apex of the triangle turned 
backwards. 
No trace of the suture between the maxillary (21) and palatine (20) bones remains : 
the alveolar border beyond the fifth socket (y) rapidly contracts to the thin vertical 
pterygoid plate (24). 
The bony palate terminates behind in an angular notch, formed by the ridges (r, r) 
before described. The bony palate forms a narrow tract, with parallel lateral borders 
gently diverging at the fore and back part of the tract, which is very slightly concave 
transversely: it is perforated by numerous foramina; two long ones, like fissures 
(Plate XXIV. V, v), opposite the interspace between the third and fourth molars, 
seem to represent the post-palatal foramina ; there are, also, some large foramina {ii, u) 
