GEOLOGICAL HISTORY OF THE CHAROPHYTA. 



73 



ing to Karpinsky (5), p. 127, Muschelkalk is not found 

 in the district named. 



Far down in the rocks of the PALEOZOIC era organ- 

 isms occur which have been ascribed to the Charophyta. 



Silurian. — From a deposit of the Silurian period on 

 the Kellerwald, remains closely resembling the vege- 

 tative parts of a Nitella are figured by Potonie (15) 

 (see Fig. 26), but in the absence of fruit it is not possible 

 to determine their nature. 



Devonian. — In the Corniferous Limestone of Ohio, 

 Meek, in 1873 (12), recorded the presence, in company 

 with marine Mollusca, of small globose bodies, " about 



Fig. 26. — Problematic Nitella-like organism from the Silurian 

 (after Potonie). 



0"05 of an inch in diameter, and each ornamented by 

 9 strongly defined and very regularly disposed spiral 

 ridges which start on one side around a minute pit with 

 perfect regularity. . . ." These, the author " can 

 scarcely doubt," are the fruits of Char a. Williamson 

 in 1880 (30) and Dawson in 1883 (2), in describing 

 similar organisms from a difi:erent locality in Ohio, 

 considered them Foraminifera, the former referring 

 them to his genus Calcisphwra, the latter to Saccamina. 

 Ulrich, in 1886 (26), again described these organisms, 

 with excellent figures, under the name of Moellerina 

 (see Fig. 27 a, b), also regarding them as Foraminifera. 

 In 1889 they were again described and figured by 



