1898-1902. No. 32.] FOSSIL FAUNAS FROM SERIES B. 



Palaeontological descriptions. 



F*laiitae, 



Algae. 



Corallinacecie. 



Solenopora Dyb. 



SoJenopora sp. 



PI. IV, fig. 1-2. 



An irregular, flat sub-liemispherical piece of limestone, with a 

 greate.st diameter of 8.5 and a greatest tiiickness of about 2 cm., that 

 even to the naked eye showed a faint surface structure, revealed by 

 studying microscopic sections the characters of a true Solenopora. As, 

 however^ the preservation of the structure is far from perfect I will i-efrain 

 from any specific determination. In fact the structural characters in which 

 the differences between the species of Solenopora may be studied are 

 so few and generally so little marked that veiy good material is neces- 

 sary in order to obtain definite conclusions. 



The radiating cells are generally perfectly or nearly straight, any 

 marked curvature being very seldom seem. The width varies from Yn 

 to Vi3 of a mm. Crossing these cell are seen the ordinary concentric dark 

 lines or shades although often very indistinctly marked. In tangential 

 sections the cells generally appear as polygonal, usually pentagonal or 

 hexagonal. In some places, however, they are more rounded. (PI. IV, fig. 1, 

 shows a part of a section with relatively rounded cells.) The cell walls 

 are usually thin; places with very thicks walls that also occur would 

 be naturally explained as due to a secondary thickening of the walls, 

 though no line corresponding to the original wall is seen in the middle 

 of the thick portions. 



The specimen probably represents a new species as yet not described. 

 The Silurian form that is described by Rothpletz from Gotland as 



