252 PALEONTOLOGY 



frequently finely serrate ; the cruwn slightly bent side ways, 

 the inner side towards the mouth-cavity. The teeth are 

 sometimes lancet-shaped, through convergence of the edges 

 towards point ; sometimes through one edge being convex and 

 the other concave, the crown is slightly curved or sickle- 

 shaped ; sometimes through use, the point is blunted. The 

 enamel is very thin, smooth, showing under the lens a slight 

 longitudinal striation, forming wrinkles. The dentine is dis- 

 posed in concentric layers ; it is not labyrinthic ; the base of 

 the tooth shows a conical pulp-cavity. These teeth indicate 

 a Saurian about ten feet in length. 



The writer cannot discern any generic, or even good specific 

 distinctions, between the teeth from the Warwickshire keuper, 

 on which in 1840 he founded the genus Gladyodon, and those 

 from the Wirtemberg keuper, on which M. Yon Meyer in 

 1844 founded the genus Bclodon, Both are nearly allied to 

 Palccosaum*. 



The two following genera are referred provisionally and 

 with doubt to the present order : — 



Genus Bathygnathus, Leidy. 



Sp. Bathygnathus borcalis, Leidy. — Allied to the C'ladijodon 

 and Belodon by the shape of the teeth is the Saurian from the 

 new red sandstone of Prince Edward's Island, North America, 

 the generic and specific characters of which have been deduced 

 by Dr. Leidy from a portion of lower jaw, containing seven 

 teeth, but with interspaces from which others have been lost. 

 The depth of the dentary bone is five inches ; a peculiarity 

 which suggested the generic name (bathns, deep ; giudhos, 

 jaw). The precise mode of implantation of the teeth is not 

 described. 



The fossil was discovered at a depth of 21 feet from the 



* Journal of il>'' Academy "I' Sciences, Philadelphia, vol. ii.. p. ^27, pi. 

 xxxiii. 



