308 



The upper maxillaries, represented in Figs. 10 to 12, bear a near resem- 

 blance to those of Edaphodon Buchlandl and E. lejitognathus, as represented 

 in Tab. 40 d, of the third volume of the Alias of Agassiz's Poissons Fossil's. 



The outer surface (Fig. 11) of each maxilla is a broad, sloping plane, the 

 inner surface a vertical plane. The upper surface is also flat, but is occupied 

 at its inner back part by a wide, deep gutter, ending forward in a pit. 



The palatine surface (Fig. 10) of the two bones conjoined at its back part 

 forms a wide, transverse concavity, nearly flat in the middle, but curving 

 downward at the outer part. The palatine surface inclines forward to the 

 anterior subacute termination of the bones. The lateral border of each max- 

 illa at the palatine surface is strongly sigmoid. 



Three large dental tubercles occupied the palatine surface of each max- 

 illa, indicated in the fossils, as seen in Fig. 10, by three depressed areas of 

 white, decomposing vaso-dentine. The largest area is posterior and internal. 

 It is broken at its back part in the fossils, but, in the entire condition, appears 

 to have been reniform in outline. Immediately in advance of this area is 

 another with an oblong cordiform outline ; and external to the largest one is 

 the third area, about as long as this, but not more than half the breadth, and 

 having a clavate outline. 



The dental columns corresponding with the three dental areas are seen 

 at the back of the maxillse, the largest one below the position of the two 

 smaller ones, as represented in Fig. 12. 



The measurements of the specimens are as follows : 



Inferior maxillary. 



Lines. 



Extreme length of bone 64 



Length of beak along the symphysis 40 



Length of anterior border of ramus 44 



Length of posterior or upper border back of the beak 26 



Width of inner surface 26 



Width of upper surface back of the beak * 24 



Width of the large postero-internal dental area 13* 



Estimated breadth fore and aft 16 



Width of external dental area - 7 



Estimated breadth fore and aft 3 



Diameter of anterior dental area fore and aft 4 



Diameter of same transversely • - 3 



* The size of the dental areas is in some measure uncertain, as in some cases they appear to havo 

 been more or less extended in the fore and aft diameter by fracture over the position of the dental 

 columns. 



