NO. 2 PRE-CAMBRIAN ALGONKIAN ALGAL FLORA 113 



Formation and locality. — Algonkian: (400a) Siyeh limestone; 

 Continental Divide at head of Kipps Creek, a branch of Mineral 

 Creek, east of Flat-top ]^Iountain, Glacial National Park. ^lontana 

 (C. D. Walcott, 1908). 



COLLENIA ? FREQUENS (Walcott) 



Plate 10, fig. 3 



Cryptosoan jrequens Walcott, 1906, Bull. Geol. Soc. America, Vol. 17, pi. 

 ir. (Species figured.) 



This form has an upright, irregular cylindrical growth, that 

 appears like paving- blocks fitted closely together. The individual 

 bodies var}^ from 2 inches (5 cm.) in diameter up to 15 inches 

 (38 cm.) or more. In the great limestone block illustrated the 

 depth of the cylindrical growth is about 16 inches (43 cm.). 



1 hope to obtain during the season of 1914 much more informa- 

 tion about this form. 



Formation and locality. — Algonkian : Siyeh limestone ; Little 

 Kootna Creek, Chief Mountain quadrangle, Montana. 



COLLENIA UNDOSA, new species 



Plate 13, hgs. I, 2; plate 14, figs, i, 2 



More or less irregularly dome-shaped, semisphseroidal, sometimes 

 roughly sphaeroidal, laminated bodies that are usually roughly con- 

 cavo-convex. They appear very much as though the under side 

 had been dug out or that the first encrusting calcareous deposit 

 was made over a lump of mud. The interior of the body is made 

 up of alternating fine and coarse laininations subparallel to the upper 

 and lower surfaces of the body. 



Individual specimens occur scattered in reddish silico-argillaceous 

 shale and .sometimes in groups of irregular forms as shown by 

 figures I and 2, plate 14. In some instances thin layers of some- 

 what- siliceous or magnesian limestone are nearly filled with broken 

 and more or less entire specimens, as shown by figure i on plate 13. 

 In sections of the roughly sphgeroidal forms it appears as though 

 a high dome-shaped specimen had been rolled over during growth 

 and a new growth started that covered the hollow under side so as 

 to enclose fragments of other specimens in the interior of the mass 

 (pi. 13, fig. 2). 



The outer surface is often botryoidal as indicated by the struc- 

 ture in the upper part of the section illustrated by figure 2, plate 

 13. The greater number of specimens are from 3 to 4 inches (7.6 



