182 STUDIES IN GEOLOGY, No. 4 



This is a well marked form, of which the thick leaf sub- 

 stance has slacked and become dissipated since the collection 

 was made. Represented by a" scant amount of material.. It is 

 of a type usually referred by paleobotanists to the allied 

 genera Eucalyptus or Myrtus, in which so many species from 

 the Upper Cretaceous to the present have been placed, and 

 it is not very different from the widespread Eucalyptus ocean- 

 ica Unger of the European Tertiary. I have compared it 

 with all of the existing genera of Myrtacese and have come 

 to the conclusion that it is indubitably a species of Myrcia. 

 Among the existing species of this genus it is close to Myrcia 

 rostrata De Candolle and Myrcia acutata Berg, both species 

 of tropical Brazil, as well as to other existing species of the 

 Amazon basin. 



About 150 fossil forms have been referred to the Myrta- 

 ceae, one-third at least having been described as species of 

 Eucalyptus. At least half of these forms occur in the Cre- 

 taceous of all parts of the world, but especially throughout 

 the Northern Hemisphere. They are especially well repre- 

 sented in North America, and the possibility that they are 

 ancestral forms of Myrcia or Eugenia has already been 

 pointed out. 20 Upwards of a score of fossil forms have been 

 definitely referred to Myrcia. These include an Upper Cre- 

 taceous, six lower Eocene and a lower Oligocene species 

 from the Mississippi embay ment region. There are several 

 in the Oligocene of Europe, one in the Miocene of Ecuador, 

 several in the lower Miocene of Chile and one in the Plio- 

 cene of eastern Brazil. 



The genus Myrcia is considered to comprise more than 400 

 existing species, and although this number may be too large, 

 it is nevertheless one of the most important genera of Ameri- 

 can Myrtacese. It ranges from the West Indies and Mexico 

 to Uruguay and Chile, and most of the species are massed in 

 the South American tropics. There are several species in the 



Berry, E. W., Bot. Gaz., vol. 59, pp. 484-490, 1915. 



