538 



BALING DON. 



dulated, divide and subdivide dichotomously in their 

 course to the periphery of the axis, where they terminate 

 in very fine irregularly bent ramuli ; some forming loops, 

 others dilating into minute calcigerous cells. The den- 



Fig. 228. 



Microscopic structure of dentine ; magnified 500 diameters. Bcdosnodon. 



tinal cells were very conspicuous in many parts of the 



th of an 



5000 



section, of a sub-circular form, and about 

 inch in diameter. 



The clear basis of the cement is almost colourless where 

 it fills the outer indentations of the dentine, and the ra- 

 diated cells are fewer here : in the rest of the entire 

 thickness of the cement they (fig. 229, c c) are very abun- 

 dant, and arranged at intervals of about thrice their own 

 diameter, which diameter is about j^-^th of an inch. 



The cetaceous character of the cement is manifested by 

 the numerous and sub-parallel cemental tubes, (fig. 229, #,) 

 which run from the outer part of the cement towards the 

 dentine, near which they terminate by fine ramifications, 

 communicating with the radiating tubular prolongations 

 of the cells. The thick cement is also traversed by vas- 



