134 



PALAEONTOLOGY 



from a short process of the central structure, which is con- 

 nected by a concave line with the adjoining process, so that 

 the whole periphery of the transverse section of the central 



Fig. 50 b. 

 Magn. section of part of Dcudrvdus biporcatus. 



coarse retieulo-vascular body of the tooth presents a crenate 

 outline. From each ray and its primary dichotomous divi- 

 sions short branches are sent oil' tit brief intervals, generally 

 at right angles with the trunk, or slightly inclined towards the 

 periphery of the tooth. These subdivide into a few short 

 ramifications like the branches of a shrub, and terminate in 

 irregular and somewhat angular dilations simulating leaves, 

 but which resolve themselves into radiating fasciculi of minute 

 dentinal lubes. Their are from fifteen to twenty-five or thirty- 



