646 UNGULATES. 



cavity was divided at its upper part into two conical prolongations, one 

 for each of the principal lobes of the crown. A few vascular canals 

 were continued from the apex of each cone into the two sub-divisions 

 or plates of each lobe. 



The dentinal tubes which radiate from the pulp-cavity and its 

 prolongations, are as remarkable as those of the tusk for their minute- 

 ness and closeness of arrangement ; but, in the tooth examined, they 

 presented at only a few points secondary undulations approaching 

 in extent to those which characterise the tubes of ivory. A few 

 tubes from the end of the vascular canal in the centre of the cone 

 of dentine go straight to the summit of that cone ; the rest diverge 

 from the vascular canals and apex of the pulp-cavity to the sides 

 of the cone of dentine, with one general primary curve, whose 

 convexity is turned towards the centre and summit of the cone, the 

 terminations of the tubes being shghtly bent in the opposite direc- 

 tion : in the roots the dentinal tubes pass, as usual, almost trans- 

 versely. 



The places where the tubuli exhibited the strong secondary 

 undulations were along a contour line at the middle of the dentine. 

 At their commencement the tubuli are straight, they then fall into 

 slight waves, and after forming three or four stronger ones at the 

 middle of their course, again resume the more feeble and irregular 

 undulations : their close arrangement renders it difficult to distin- 

 guish bifurcation from decussation ; yet in some parts I had clear 

 evidence of division of the main tubes, which left little doubt that 

 the usual dichotomy prevailed, to produce the same dense arrange- 

 ment of tubuli at the broad peripheral as at the narrower central 

 part from which the tubes diverge. 



The number of minute lateral branches is extreme ; especially 

 in the peripheral third part of the tube. Those from near the usually 

 bifurcated terminations of the tubes are lost in the stratum of minute 

 opake cellules near the outer surface of the dentine. Many of the 

 terminal bifurcations of the tubuli here bend back, and form loops 

 by anastomosing with adjoining branches. 



The fibres of the enamel present a minutely jagged, or cre- 

 nate outline, but are not crossed, bv transverse lines. Their 



