the sections corresponds to that in tlie diagram, figure 1, so that a, 

 section 2, is the cross sections of canal a. figure 1, etc., hgf being a cross 

 section of the united vessels /(, g, and /, figure 1. V of section 2 is the 

 cross section of the large canal in the caudal portion of the palatine. Sec- 

 tion .3 differs only slightly from 2. Here e has united with ligf to form 

 hgfc. and d is about to unite. Section 4 shows d united, and the system 

 opening out to the surface at ;'. (See point i, fig. 1.) The areas bounded 

 by curved lines in all of the sections, and marked o, 6, c, d, etc., in sec- 

 tion 4, represent cross sections of bases of the successive fangs. Note 

 the shape of these areas near the caudal end of the sections, showing that 

 more than half of the external portion has been absorbed. In section 2, 

 very near the upper margin of the figure, are shown five tiny openings on 

 the external side of the bone, one corresponding to each of the areas b, c. 

 d, e, and /. These appear on the margins of the sections in figures 3 and 

 4, well on the ground surface in figures 5 and 6. and are not to be seen in 

 section 7 or thereafter. Not many of the palatines show the openings of 

 this series of canals. Section 5 shows h, g, f, e and d disconnected, and 

 canal a very near the mesial surface. Figure 6 shows no important 

 change. Figure 7 shows canal « divided. Figure 8 shows canals c and ') 

 united to form cb, which opens to the mesial surface. The section shown in 

 figure 9 passes above canals c and 6, and shows a about to open to the 

 surface. 1' has become much elongated in cross section. No drawing was 

 made at level B-X. In section 10, V has branched to form the gi'oup M, 

 and a has opened to the mesial surface, as shown in all sections following, 

 the portion cephalad to the line B-B not being ground any further, as 

 shown in the diagram, figure 1. Section 11 indicates further branching of 

 the canals in the caudal end of the bone. Section 12 shows these canals 

 slightly grouped again, and in figure Vi the four external canals show 

 much elongated cross sections. Figure 14 shows these four canals 

 slightly enlarged, and a fifth one (r/) just mesial to them. These five 

 proceed dorso-cephalad to the surface, as shown in figure 1. The oval 

 cavity (It) is not a canal, but only a space in the bone, probably abnormal. 



Figs. 15 and 16. — Figure 15 shows a longitudinal vertical section of a 

 palatine, not quite median, but taken along the line D-D in figure 16, 

 which is a ventral view of the same bone after the portion ventral to the 

 line C-C (fig. 15) had been ground away. The areas a, b, c, d, e, /, etc., 

 represent the vertical sections of the successive bases of the palatine 

 fangs, thus showing the relation of the osteodentine of which they are 

 composed to the true bone above. The lettering in figure 16 corresponds 

 to that of figure 1. X H- No. 837. 



Fig. 17. — A longitudinal vertical section of a palatine which has been 

 described and figured as E. pctrosus by Stewart (1900). A mesial view 

 of the same bone is shown in plate III, figure 5, upper figure. This pala- 

 tine differs from figure 15 in having a dorso-cephalic process, and in the 

 different outlines of the vertical sections of the successive osteodentine 

 bases. The dorsal ends of the first five, a. b. c, d, e. are bent forward. 

 Bases 6 and e seem to have had some irregularity in growth. Evidently 

 the process above base a is not simply a stage in the production of the 

 fang, but is a character that was always present in this specimen and 

 never occurred in the development of the palatine shown in figure 15. 

 X %. No. 16. 



