13 



Measurements. m. 



Long diameter of dental surface Oil 



Short diameter of dental surface 007 



Thickness of plate 003 



There are six ridges in the length. 

 Ceratodus hieroglyphus, sp. nov. 



This species is materially different from the last, and was more 

 abundant, judging from the occurrence of its remains. 



The dentigerous plate is thin and dense, and has the appearance 

 of a short toothed comb with a handle. The tooth-like points are 

 the extremities of low ridges, which are arranged nearly at right 

 angles to a wide longitudinal elevated half of the osseous base. 

 They are separated by shallow grooves from each other, and are 

 not continuous with the basis just mentioned, which rises abruptly 

 above them. They are smooth. The " handle" above alluded to 

 is triangular in section having two bevels on the side supporting 

 the tooth ridges. The lower face of the bone is smooth. 



Measurements. m. 



Total length 013 



Length of dentigerous portion 010 



Total width 0045 



Width of dentigerous portion .0020 



There are thirteen teeth in the length. 

 Myledaphus bipartitus, Gen. et sp. nov. 



Char. Gen. — Crowns of the teeth molar in character, truncate, 

 wider than long, standing table-like on the root. The latter par- 

 taking of the shape of the crown, short, straight, split equally and 

 at right angles to the greatest diameter of the tooth. The crowns 

 form a pavement having a regularly hexagonal outline. Their 

 composition is different in the halves on each side of a line which 

 divides the crown equally, running in the long direction. On one 

 side the dentine is striate at right angles to the long diameter ; 

 the structure is not distinguishable by the hand lens on the oppo- 

 site side of the line. 



The affinities of this genus cannot now be stated, but the form 

 of the root recalls the Elosmobranchii, and that of the crown, 

 some of the rays. 



Char. Specif. — The staining on opposite sides of the line that 

 divides the crown, is different, on the one paler than on the other. 



