DESCRIPTION OF PLATE III 



Drawings from teased preparations of enamel, except figs. 5, 6, 7, and 8, which 

 are from sections. 



FIG. 1. Double-grooved prisms (Elephant), r. Ridges ; g. grooves. The 

 ridges are often seen projecting beyond the extremities of fragments. 



FIG. 2. Single-grooved prisms (Elephant), r. Ridge ; g. grooves. 



FIG. 3. Two double-grooved prisms, transverse above (Elephant). 



FIG. 4. Fragments of prisms in transverse fracture (Elephant). 



FIG. 5. Four prisms from a section (Elephant) showing surface marking 

 and prominence of the ridge at r. Compare with photograph, fig. 26. 



FIG. 6. From Elephant : bridges in transverse section. The inter- 

 prismatic substance appeared dark and the bridges are very conspicuous 

 as white lines. 



FIG. 7. Elephant. From a section showing a wing process in the enamel. 

 Compare with photograph, fig. 27. 



FIG. 8. Elephant. From a section showing ridges and grooves, r. Ridges; 

 g. grooves. Compare with photograph, fig. 27. 



FIG. 9. Two prisms from Elephant, showing needle-splitting (n) and 

 inter- columnar bridges (6). 



FIG. 10. Fragment of Elephant enamel in transverse section. Two 

 entire double concave prisms are seen projecting, with feather edges and 

 intercolumnar bridges (6). 



FIG. 11. Fragments of prisms seen obliquely (Elephant). Compare with 

 photograph, fig. 28. 



FIG. 12. a, b, c. Wing processes and membranous layers in Macropus, 

 showing needle-splitting, wings, and bridging. 



FIG. 13. Fragment of Macropus enamel. Membranous laminae at right 

 angles to direction of prisms. 



FIG. 14. Wing process, human enamel. 



The drawings of the teased preparations were made by direct observation 

 under the microscope, and are magnified about 400 diameters ; figs. 6 and 1, 

 from sections, are x 800. 



