608 ON THE STRUCTURE OF THE ENAMEL IN THE PRIMATES. 



Plate V. 



Fig. 1. Section of tlie occlusal surface of the left iipper molar of Indris ; the photo- 

 micrograph taken from the same tooth as the illustration shown in PI. I. 

 fig. 2. The tubes {i) pass but a short distance into the enamel (e). 

 The pattern of the enamel is clearly shown, the enamel rods (e.r.) having 

 straight margins and showing a fine granular structure. X 450. 



Pig. 2. Section of a molar of Chiromys. The dentinal tubes terminate at the amelo- 

 dentinal junction. The pattern of the enamel is similar to that of the 

 other Mascarene Lemurs. X 500. 



Pig. 3. Section of enamel of Semnopitkecus. X 450. 



Plate VI. 



Fig. 1. Section of a cusp of a molar of Seniiacodon, showing the presence of tubes 

 {t) in the enamel (e). X 275. 



Fig. 2. Transverse section of an incisor of Galago, showing the enamel rods (e.r.) cut 

 across and having a circular form separated one from another by a con- 

 siderable amou.nt of interprismatic material (i.p.m.). X 300. 



Fig. 3. Section of a molar of Nycticehtis, showing the slight amount of penetration 

 of the "tubes" {t) into the enamel, whilst many end in a bulbous spindle 

 (J) similar to those shown in the enamel of Callithrix (PI. IV. fig. 3). 

 X 300. 



Fig. 4. Section of an incisor of Perodicticus potto, showing the passage of tubes (t) 

 and an enamel pattern identical with that seen in G-alago and in Tarsius. 

 X340. 



Plate VII. 



Fig. 1. Section of an incisor of Macropws riificollis, showing the enamel rods {e.r.), 

 cut transversely, lying in rows which are separated by sharply-defined 

 areas of interprismatic material {i.p.m.). The "tubes " of the enamel are 

 seen as black dots {t). X 1500. 



Fig. 2. A transverse section of the enamel of a molar of Folymastodon, etched to 

 show the structure. The horseshoe-shaped bodies with bulbous ends {h.s.) 

 would suggest sections through an elongated spiral since they never form 

 complete rings. X 275. 



Fig. 3. Transverse section through the enamel of the lower incisor of Folymastodon, 

 showing a similar condition to that seen in fig. 2, but demonstrating a 

 finely granular structure of the areas embraced within the horseshoe- 

 shaped bodies. X 400. 



Fig. 4. Longitudinal section of the enamel of a molar. X 480. 



Fig. 5. Unetched section of a molar of Folymastodon, showing the passage of tubes 

 {t) from the dentine {d) into the enamel (e). X 300. 



