559 
cations of it have appeared in certain regions, that is, the cartilage 
cells are greatly enlarged and are degenerating. The columella is 
undergoing this process but not throughout its entire length, only 
in that area which chondrified from the proximal center. The distal 
eae . Te i — | u T. 
‘ 
vic. | sees =—— no. 
3 \ 
ax 
En‘ 
T 

Fig. 9. Young adult of 19 mm. carapace measurement. Abbreviations the same as before. 
portion, including the interhyale, has remained hyaline cartilage. 
In a dissection of an older adult (carapace measurement, 67 mm.), 
of Chrysemys pieta, the columella proper was found completely ossi- 
fied, and the extra-columella, cartilaginous, thus indicating that this 
condition of the two parts of the columella persists throughout life. 
Summary. 
I. In an early precartilage stage the condensations of the skeletal] 
elements (hyoid cornu, interhyale and columella auris) of the hyoid 
arch are continuous. 
