Carboniferous Algal Deposits. 349 



algal material. The exteriors are irregular through the 

 presence of little cylindrical- sided domes and their sepa- 

 rating depressions. The elevations arise from one 

 another and there is great irregularity in shapes, sizes 

 and degrees of divergence. 



The interior structure consists of very thin and closely 

 placed concentric laminae and these repeat the irregulari- 

 ties of the exteriors. A depression on the surface is apt 

 to be continued into the interior by small lines or streaks 

 of fine sand and mud. These streaks are interpreted as 

 arising from small quantities of mud and sand becoming 



Fig. 3. 



Fig. 3. Ottonosia laminata n. sp. X 2. Microphotograph of section of 

 the holotype. The white streak across the middle is a cross section of the 

 shell nucleus. Crouse limestone, near Otto, Kans. 



lodged in the depressions between the domes. Some 

 tube-like structures which penetrate portions of the inte- 

 rior may have been produced by the boring of annelids 

 or mollusks, or they may be molds of the thalli or algae. 

 These are also filled with fine sand and mud. The laminae 

 vary in thickness ; at one place eight were distinguished 

 in a thickness of five millimeters ; at another place only 

 five laminae are present in the same thickness. 



Relationships. — In general appearance the coenoplases 

 of this genus resemble those of Sphaerocodium Rothpletz 

 from the Silurian of Gotland, but differ in the general 

 absence of a spherical form and in the nature of the irreg- 

 ularities of the surface. Internally, Sphaerocodium is 

 said to have concentric tubes around the nucleus; such 



