2 University of Michigan 



point. The tooth is of medium thickness and is built up of 

 superimposed laminae. The surface is marked by numerous 

 minute pits which can be seen (when the surface is damp- 

 ened) to be the terminations of vertical canals. The bottom 

 of the grooves is marked by irregular depressions into which 

 the canals open as upon the rest of the surface. 



Remains of fish are very scarce in the Dockum beds. With 

 the exception of a few small conical teeth which may belong 

 to fish, this is the only one found in a collection of several 

 hundred teeth. It is especially interesting in its suggestion of 

 the occurrence of palustral areas in an otherwise arid or semi- 

 arid region ; this suggestion is strengthened by the discovery 

 of a bed of Unios of as yet undetermined species, by the 

 abundance of plant remains in an advanced state of decom- 

 position and by the occurrence of gypsum in restricted areas. 

 By far the larger number of remains found in these beds are 

 of Phytosaurians and large Stegocephalians. 



For this new species of Ceratodus I would suggest the name 

 C. dorotheae in recognition of the work of Miss Dorothy 

 Doughty of Post City, Texas, an enthusiastic and intelligent 

 collector. 



Right palatal tooth of Ceratodus dorotheae X 6 



