Maryland Geological Survey 475 



The most ancient horizon recorded for this genus is that of the 

 Potomac Group, Professors Fontaine and Ward having described no 

 less than thirteen species from strata of that age in Maryland and 

 Virginia. This proves to be altogether too large a number, however, 

 as a critical examination of the material shows that the three forms C. 

 arcinerve Fontaine, C. marylandicum Fontaine, and C proteoides Fon- 

 taine are not referable to Celastrophyllum at all. C. tenuinerve and C. 

 obovatum of Fontaine are included in that author's C. latifoUum while C. 

 ohtusidens Fontaine and 0. pulchrum Ward are included in G. acutidens 

 Fontaine. The genus is not present in the older Potomac, i. e., the 

 Patuxent or Arundel formations, but is present in considerable force 

 in the Patapsco formation with four species in Maryland and three 

 additional species in Virginia, one of the latter being identical with 

 a form from the New Jersey Raritan. The latter formation has nine 

 recorded species and embracing the largest leaves which have been 

 referred to this genus. The Dakota Group also has several species as has 

 the Cenomanian and Senonian of Greenland and Europe. A large display 

 of these forms is also made in the Paleocene of Europe from which 

 Saporta and Marion have described the well preserved remains of seven 

 species of Celastrophyllum and four species of the allied Celastrinites. 



Few species have been described from strata younger than Eocene, 

 the more modern leaves of this type being more readily correlated with 

 the various living genera of this family. 



The living descendants of the American fossil forms are probably 

 to be found among those species which inhabit the American tropics or 

 those which took refuge in the mountains of eastern Asia after the 

 retreat of the Pleistocene glaciers. 



Celastrophyllum dentioulatum Fontaine 

 ■ Plate XC, Figs. 1, 2 



Celastrophyllum denticulatum Fontaine, 1890, Mon. U. S. Geol. Survey, vol. 

 XV, 1889, p. 306, pi. clxix, fig. 10; pi. clxxii, fig. 7. 



