iv.] MARSUPIALIA. 49 



As to the other vertebrae, in the Kangaroos the transverse 

 processes are long and slender, and (including the seventh) 

 have a very small perforation close to the base. The inferior 

 lamella arises near the base of the process, and is very 

 large in the sixth, but generally absent in the seventh 

 vertebra. 



In the Wombat, the bodies are wide and depressed. The 

 transverse processes are perforated in all ; the inferior 

 lamella of the sixth is much developed antero-posteriorly. 

 The spines of all are rather short. 



FIG. 19. Inferior surface of atlas of Thylacine (ThylacimiS cynocephahts), 5. h dis- 

 tinct ossification in centre of inferior arch, with pointed hypapophysial pro- 

 jection. 



In Perameles lagotis the greater part of the transverse pro- 

 cess of the axis is ossified separately from the rest of the 

 vertebra, and remains sometime distinct, as in the Mono- 

 tremata. In this genus, as in the other carnivorous Marsu- 

 pials, the inferior lamellae of the transverse processes of the 

 fourth, fifth, and sixth vertebrae, but especially of the latter, 

 are particularly large. 



Some species of American Opossums (as Didelphys 

 virginiana and its nearest allies) have the spinous processes 

 of the second, third, fourth, and fifth cervical vertebrae very 

 high, square, and massive, and being closely applied to each 

 other by flattened surfaces, form a solid wall of bone along 

 the top of the neck, 



