326 DENTICLES ON THE SNOUT OF XIPHIAS GLADIUS. 



Fig. 4. The same. A number of denticles (c^) arc seen resting on their pediments (p). 

 The connecting transhicent zone {ts) is seen to correspond witli the 

 junction of epithelium (e) with mesoderm ()«)• i'le continuous 

 scaffolding of bone which supports the denticles is not cr.nnected at 

 any point in the section with the premaxilla. X -iO. 



¥ig. 5. The same. A section showing the relationship of the premaxilla to the 

 secondary' bone. X 40. 



Plate II. 



Fig. 1. Histiopliorus, Photograph of the surface of the rostrum showing 

 developmg denticles {d) lying in widely open crypts. The erupted teeth 

 are anchylosed in place. X 7'o. 



Fig. 2. The same. Photomicrograph of a portion of a section of the rostrum 

 showing two denticles (d) attached to the surface of the rostrum. X 40. 



Plate III. 



Fig. 1. Blennius. Photomicrograph of a section of the pharyngeal plate showing a 

 developing tooth {d), its pediment {p), and connecting substance {tz). 

 The epithelium {e) extends down to the limits of the tooth. 



The pediments of the erupted teeth are joined one to another l)y means 

 of trabeculae of bone [tr). X 40. 



Fig. 2. jPagellus oentrudontus. Photomicrograijh of a developing tooth showing 

 the continuity of the cells of the dentinal papilla {d.p). X 90. 



Fig. 3. The same. Photomicrograph of a transverse section through the bone 

 underlying the teeth, showing the pediment {p) of a newlj' erupted tooth 

 becoming attached to its neighbours by trabecula3 ((?•). X 45. 



