736 
PROFESSOR OWEN ON THE MEGATHERIUM. 
in the twelfth, and becomes thicker and more obtuse in the remaining dorsals and in 
the lumbar vertebrse. There are no anapophyses. 
In the skeleton on which these observations were made, there is a peculiarity that 
well illustrates the serial homology of the diapophyses of the dorsal and lumbar 
regions. The tubercle disappears in the penultimate pair of ribs, and the diapophysis 
is reduced in the thirteenth dorsal vertebra to a sh^-t rough tuberosity {d’)-. but in the 
last pair of ribs the tubercle with its articular surface reappears, and the diapophysis 
{d) resumes its normal size and articulation with the rib, which inclines forwards at 
its commencement. In the first lumbar vertebra the diapophysis {d) suddenly 
increases in length and breadth, which increase is doubtless due to the ossified and 
coalesced rudiment of a rib (/>/). 
In the Meminna {Moschus meminna), wfith c? 13, / 7, the metapophysial tubercle 
appears above the diapophysis of the anterior dorsals, projects as a distinct process 
midway between the diapophyses and prozygapophyses of the seventh to the tenth 
dorsals inclusive ; gets upon the prozygapophysis of the succeeding dorsals and an- 
terior lumbars, and subsides in the penultimate lumbar vertebra. The tubercle has 
disappeared on the tenth rib, and does not reappear in those that follow : but the 
diapophysis continues on the last four dorsal vertebrae, increasing in length upon the 
last two, and plainly showing the nature of the longer diapophyses in the lumbar 
region. 
In the Elk {Alces Americana), with c? 13, Z 6, the metapophysial ridge becomes 
distinctly developed upon the diapophysis of the eighth dorsal, is a tubercle on the 
ninth, forms a process exceeding in length the diapophysis in the tenth and eleventh 
dorsals, and subsides to a tuberosity again in the twelfth and succeeding vertebrae, 
where its position has changed from the diapophysis to the zygapophysis. There is a 
slight trace of an anapophysis in the last lumbar vertebra. 
In the Equine Antilope {Antilope equina), with d 13, Z 6, the metapophysis is de- 
veloped from the fore-part of the diapophysis of the second to the ninth dorsals 
inclusive, where it begins to be transferred to the outer side of the prozygapophyses, 
from which part it projects in the last four dorsals, and in all the lumbar vertebrae. 
There is a short anapophysis in the last two dorsals, but not in any of the lumbar 
vertebrae. 
In the Gnu {Catohlepas Gnu), with d 14, Z 6, there are no anapophyses; the met- 
apophyses resemble those in the Equine Antilope. 
In the Common Ox {Bos Taurus), with d 13, Z6, the metapophysis, beginning as a 
rudimentary tubercle at the anterior dorsals, increases in size in the tenth, eleventh 
and twelfth dorsals, in which it is transferred from the diapophysis to the prozyga- 
pophysis. 
In the Aurochs {Bison Europceus), with ^Z 14, Z 5, the metapophysis is most distinct 
on the ninth, tenth and eleventh dorsals, in which it ascends to the prozygapophysis. 
In the Giraffe {Camelopardalis Giraffa), with tZ 14, lb, the metapophyses com- 
