NO. 2 PRE-CAMBRIAN ALGONKIAiSr ALGAL FLORA IO9 



■ Mode of gro-u'th. — As far as indicated by the specimens collected 

 by Mr. M. Collen the cellular structure grew with the tubes more 

 or less parallel to the bottom and in some instances upright or at 

 right angles to the bottom. The section illustrated by figure i, plate 

 18, shows that it was formed of four rows of tubes parallel to the 

 under and upper surface of the layer of limestone. The specimen 

 represented in part by figure 2, plate 17. and figure i, plate 18, 

 is 36 cm. in length, with a depth of 18 cm. It has 12 rows of 

 tubes, and it is evidently part of a nuich larger mass. The tubes 

 vary from i to 2 cm. in diameter. 



Genotype. — Greysoiiia basaltica, new species. 



Stratigraphic range. — Lower portion of Xewland limestone. 



Geographic distribution. — Eastern slope of Big Belt Mountains, 

 Montana. 



Observations. — It is difficult to conceive of the tubular structure 

 of Grevsonia as a deposit made by algae, but with the example of 

 the varied forms of recent deposits made by the Blue-green 

 algae ( Cyanophyce?e ) and the other fossil forms described in this 

 paper we are prepared to consider Greysonia as of algal origin. 

 There is evidently much yet to be learned of its mode of growth, 

 but that is a matter of further field study. 



GREYSONIA BASALTICA, new species 



Plate 17, figs. I, 2; plate 18, figs, i, 2 

 The generic description contains what is known of this species 

 from the material now in the collection. 



Formation and locality. — (400c) Algonkian, Beltian series: New- 

 land limestone; eastern slope of Big Belt Mountains, 8 miles (12.8 

 km.) west of White Sulphur Springs, at forks of Birch Creek, 

 Meagher County, Montana. 



COPPERIA, new genus 



A tubular structure formed of thin partition walls that are thick- 

 ened at the junction of three or more tubes. The tubes are in 

 echelon arrangement and break out in plates as shown by figure 

 2, plate 19. 



In the specimen illustrated by figure 3, plate 19, the four lower 

 layers of tubes were formed in a horizontal position and above them 

 the growth was irregular, the tubes curving and also bending up to 

 the surface of the layer. 



