ENAMEL 67 



the prisms are very much larger than those of human 

 enamel and their structure is more easily made out both in 

 sections and in teased preparations. The average diameter 

 of the prisms of Elephant enamel is 10 to 12 ^, while that of 

 human enamel is 4 to 5 ju. 



The interlocking of the prisms is more general in the Elephant 

 Elephant ; in fact, over the surface of a large section it is el 

 difficult to find a single prism that shows the usual rounded 

 or polygonal form. On examining a transverse section of 



FIG. 25. Enamel of molar of Asiatic Elephant. ( x800.) 



the enamel of the Elephant's molar, which includes the 

 neighbouring areas of dentine and cement, the prisms 

 are seen both in transverse and longitudinal section, the 

 former predominating, and the transversely cut prisms 

 appear at first sight to overlap one another like tiles on 

 a roof, or the scales of a fish (figs. 25 and 26). Teased pre- 

 parations of the enamel show, however, very clearly that 

 these prisms have a concavo-convex cross -section and are 

 deeply grooved posteriorly (Plate III, figs. 1, 2, 3). 



The groove may be single, when there is a prominent Grooving 

 ridge to be seen on each side of it, or they may be double, as pni 

 is usually the case, when there is, in addition, a pronounced 



F 2 



