RUMINANTS. 539 



The enamel extends to the beginning of the division of the 

 crown of the tooth into fangs, and consequently for some distance 

 into the socket in young Ruminants. The enamel covering the 

 outer sides of the flattened crowns of the incisors is thicker than 

 that upon the inner sides of the same teeth. The fibres are unusually 

 slender, not exceeding ^th of an inch in diameter. 



Retzius has accurately and clearly described both the coronal 

 and radical cement in the teeth of Ruminants. He says, " I found 

 only a thin layer on that part of the teeth which was covered by 

 enamel : the cement was more thickly deposited round the ends of 

 those roots which were nearly closed, and in the clefts or enamel- 

 folds of the crown. Both the calcigerous cells and tubes were large 

 and very irregularly formed. In the thin layer of cement covering 

 the enamel, the cells appeared more like reticular vascular glands 

 than actual cavities : many of these are extended into oblong or 

 many-pointed figures of considerable length ; and, besides these, 

 larger (vascular) canals proceeded from within, pretty parallel but 

 thinly scattered. The said gland-like cells were about ^^Jh of an 

 inch in long diameter, the vascular canals about i„th of an inch. 

 It is most worthy of remark that the cemental cells entered into 

 very large and numerous communications wdth the (minute opake) 

 cells in the outer part of the dentine. The cement was very porous 

 in the clefts of the tooth, and manifested still less regular tubes and 

 cells than in the situations above described. The quantity of cement 

 in the Ox is far greater than in the Sheep : the above-described 

 coarse tubes (vascular canals), were here regularly branched and 

 proceeded likewise in an almost horizontal direction on the sides 

 of the teeth. But the cells were smaller and more regular than in 

 the sheep : they were very closely aggregated, approaching the 

 circular form and about g^jth of an inch in diameter." In PI. 109, 

 fig. 4, is given Dr. Erdl's figure of a portion of the cement from 

 the root of the molar of a Calf, as seen by reflected light : the 

 opake calcigerous radiated cells are clustered together chiefly 

 towards that side which was next the outer surface of the cement: 

 and from these cells proceed the cemental tubes, which here and 

 there dilate into smaller and more simple cells, as they approach the 

 dentine. 



