PROFESSOR OWEN ON THE MEGATHERIUM. 
385 
Si. Pubis. 
65- Femur. 
66. Tibia. 
66'. Patella, 
67 . Fibula. 
67'. Fabella. 
a. Astragalus. 
cl. Calcaneum. 
s. Scaphoides. 
ce. Ectocuneiform. 
h. Cuboides. 
II. Rudimentary metatarsal of second 
digit. 
III. Third digit. 
IV. Fourth digit. 
V. Fifth digit. (There is no rudiment 
of the first or innermost toe of the 
hind foot in the Megatherium.) 
PLATE XVIII. 
Typical vertebrae in the Megatherium. One-fourth natural size. 
Fig. 1. Fifth dorsal vertebra, or natural segment of the skeleton, c. Centrum, c'. arti- 
cular tubercle for head rib ; n, neurapophysis, n', neurapophysial surface 
for neck of rib ; d, diapophysis, d', diapophysial surface for tubercle of rib ; 
2 , anterior zygapophysis ; m, metapophysis ; ns, neural spine ; pi, pleurapo- 
physis or ‘vertebral rib’; c", head; n!', articular surface on upper part of 
the neck ; d”, articular surface on tubercle ; h, haemapophysis or ‘ sternal 
rib,’ s', s’, its condyles; hs, haemal spine, or ‘sternal bone;’ s",s", articular 
surfaces for haemapophysial condyles. 
Fig. 2. First caudal vertebra, n. Neural arch ; p, parapophysial part, d, diapophysial 
part, pi, pleurapophysial part, of compound transverse process ; hy, hyp- 
apophyses ; h, haemapophysis, hy’, articular surface for its own vertebra, 
which is in advance; hy”, articular surface for succeeding vertebra. 
PLATE XIX. 
Fig. 1 . Seventh dorsal vertebra, front view. 
Fig. 2. Seventh dorsal vertebra, back view. 
Fig. 3. Seventh dorsal vertebra, side view. 
Fig. 4. Sixteenth dorsal vertebra, front view. 
Fig. 5. Sixteenth dorsal vertebra, back view. 
All the figures are drawn, minus the haemal arch, one-fourth natural size, 
c’. Articular tubercle for the head of the rib ; ri, neurapophysial articular 
surface for the neck of the rib ; d, diapophysis, d’, diapophysial articular 
surface for tubercle of rib ; m, metapophysis, mz’, metapophysial arti- 
cular surface ; a, anapophysis, a’, anapophysial articular surface ; p, par- 
apophysis, pa, parapophysial articular surface ; 2 , anterior, z’, posterior, 
mz, mid-anterior, mz’, mid-posterior, zygapophyses ; ns, neural spine. 
3 F 2 
