PROFESSOR OWEN ON THE MEGATHERIUM. 
741 
In the Ai {Bradypus triductylus), with 16, / 3, both met- (m) and an- {a) apo- 
physes, Plate XLIX. fig. 1 7? ai’e present, and the former are more distinctly developed 
than in the Unau : they are, however, restricted, as in that species, to a very few ver- 
tebrae. The rnetapophysis {in) is first developed as a distinct, though small obtuse 
conical process from the fore-part of the diapophysis {d) of the penultimate dorsal 
vertebra (d is) ; it increases in size and approaches the prozygapophysis ( 2 ) of the 
last dorsal (d is); ascends upon the outside of that process, and becomes more 
obtuse in the first (l 1 ) and following lumbar vertebrae. 
In the Orycteropus capensis, with 13, / 8, an accessory tubercle is developed 
upon the diapophysis of the seven anterior dorsal vertebrae, which divides near the 
eighth into rnetapophysis and anapophysis. These progressively increase and diverge 
from one another in the succeeding dorsals, and in the first lumbar vertebra the inet- 
apophysis projects upwards, outwards and forwards upon the outside of the anterior 
zygapophysis ; whilst the anapophysis extends backwards from the back part of the 
diapophysis, which it equals in length. The anapophysis decreases in size in the fol- 
lowing lumbar vertebrae and disappears in the last*; the rnetapophysis also decreases 
in size, but is continued throughout the lumbar series and along part of the sacral. 
The transverse processes of the three anterior sacrals join the ilia ; those of the three 
posterior ones coalesce to form a broad depressed plate, with the posterior angles 
produced, but not joining the iscbia. A long and strong process is sent out from 
above the tuber ischii. Metapophyses are developed from the outside of the ante- 
rior zygapophyses, as far as these extend along the caudal series, viz. to the eighth 
vertebra ; beyond these the metapophyses are developed, independently of the zyg- 
apophyses, to near the termination of the tail. 
In the Long-tailed Armadillo {Dasypiis longicaudus, Pr. Max.), with d\\,lb, the 
metapophyses commence, abruptly, as long slender obtuse processes, on the seventh 
dorsal (Plate XLIX. fig, 18, d 7 , m ) rising midway between the diapophyses {d) and 
prozygapophyses ( 2 ), and projecting obliquely upwards and forwards : they pass upon 
the outside of the base of the prozygapophyses of the eighth dorsal (n s, m), develope 
an articular surface from the inner side of their base for an extension of the surface of 
the zygapophysis upon its outer side in the ninth and succeeding dorsals; in the eighth 
dorsal they also develope a second articular surface from the under part of their base 
for articulating with the anapophysis of the seventh dorsal. The metapophyses in 
the following vertebrae, retaining their tvvo articular surfaces, progressively increase 
in length until they exceed the neural spines in this respect in the last three lumbar 
* I have ascertained that the vertebral column of the so-called ‘Ant-eater’ exhibited by Dr. Melvillk 
at the meeting of the Zoological Society, on December 12, 1848, in order to demonstrate “that the Edentata 
had no posterior or backwardly projecting processes from the diapophyses,” is not of a true Ant-eater, but of 
an Orycteropus, in which, although the development of the anapophyses is much less than in the sj)ecies of 
Myrmecophaga, they are nevertheless sufficiently recognizable. In no order of Mammals, as 1 shall presently 
show, are the ‘ anapophyses ’ or ‘ backwardly projecting processes ’ more extraordinarily developed than in the 
Edentata. 
5 c 
MDCCCLI. 
