SKELETON OF QUADRUMANA. 



513 



nigrifons the metapophysis begins to be developed in the middle 

 dorsal vertebrae, and, in the tenth, projects above, but distinct 

 from, the diapophysis. In the eleventh the diapophyses have 

 disappeared, and the metapophysis is on the outside of the prozyg- 

 apophysis. From this vertebra a well-marked anapophysis is 

 developed, which is continued from all the succeeding vertebrae. 

 The diapophysis reappears upon the first lumbar, and increases 

 in length and breadth as the other lumbar vertebrae approach the 

 sacrum. The centre of motion of the back is indicated by the 

 vertical spine of the tenth dorsal vertebra, towards which those of 

 the other dorsal and of the lumbar vertebrae incline. 



343 



Skeleton of the Aye-aye, (Cfieiromys madajascariensis.) B. Hand of Potto. 



In the Aye-aye ( Clieiromys), fig. 343, the true vertebra? describe 

 one slight curve convex backward from the middle dorsal to the 

 penultimate lumbar, beyond which there is a slight bend in the 

 opposite direction to and including the sacrum. The bodies of 

 the dorsal vertebra? gradually lengthen and deepen as they ap- 

 proach the loins, with a narrower and at last almost carinate 

 under surface. The diapophysis, longest on the first dorsal, very 

 gradually shortens to the eleventh, where the beginnings of the 

 metapophysis and anapophysis are manifest. These processes 

 become widely separated in the twelfth and thirteenth dorsals, 

 and the diapophysis is lost. The neural spines are of equal length 

 throughout the dorsal series. The vertical one is on the eleventh 



VOL. II. L L 



