352 W. H. Twenhofel — Algal Deposits. 



additional fact that no matter what the nucleus may be, a 

 fusiform shape tends to be developed, makes it quite cer- 

 tain that they are of organic origin. 



The ccenoplases are about the shape and size of Fusu- 

 lina, but are generally a little larger and more robust. 

 Each has a small fragment of rock or shell for a nucleus. 

 In one observed instance the nucleus consists of a small 

 pellet of fine-grained sand and mud. It is probable that 

 anything would serve. Dimensions range to a length of 

 about 7 millimeters and a thickness of about 4 milli- 

 meters. The exteriors are imbedded in the rock, but they 

 appear to be smooth or only slightly irregular. The 

 interior structure consists of thin concentric laminae of 

 which there are from 4 to 6 to a millimeter. No radial 

 structures of any kind were observed. 



All of the specimens are so discolored by limonite that 

 it was not possible to photograph them in thin section. 

 The greater part of the limonite occurs within the 

 ccenoplases, the surrounding matrix generally being com- 

 posed of quite clear calcite. It is considered quite cer- 

 tain that the limonite was precipitated in the ccenoplase 

 at the time it was formed and that there is some genetic 

 connection between the limonite and the algae which were 

 responsible for the ccenoplases. 



Relationships. — In method of development the cceno- 

 plase of this genus resembles all others of concentric 

 laminated structure. The small size, the general absence 

 of a wrinkled exterior and the tendency to assume a fusi- 

 form shape are rather marked features of difference. 



The generic name is taken from Osage County, Okla- 

 homa, on the northern border of which the ccenoplases 

 occur in abundance. The genotype is Osagia incrustata 

 n. sp. 



Osagia incrustata new species. 

 Fig. 5. 



The generic description gives the characters of the spe- 

 cies, the specific name calls attention to the incrusting 

 habit. 



Horizon and locality. Foraker limestone, Pennsylva- 

 nian, Ekler Canyon, southern Cowley County, Kansas 

 and northern Osage County, Oklahoma. 



The holotype and the paratypes are in the collection of 

 the writer. 



University of Wisconsin, 

 Madison, Wis. 



