NO. 2 PRE-CAMBRIAN ALGONKIAN ALGAL FLORA II5 



CAMASIA, new genus 



Compact layer-like growth with numerous irregular tube-like 

 openings that give a spongoid appearance in cross sections of the 

 tubes (pi. 12, figs. I and 2). The openings or tubes are smallest at 

 the base, increasing inside toward the summit of the layer. In the 

 specimen illustrated by figure 2, plate 9, they are very small and all 

 are inclined in one general direction. In another large specimen 

 (pi. 12, fig. 2) the irregular tubes and openings extend obliquely 

 to the left about one-third of the way and then very irregularly in 

 an oblique direction to the right to near the top of the layer. 



A row or chain of cells derived from Camasia spongiosa is shown 

 by figures 2-4, plate 20, and a cluster of round cells by figure 5. 

 These cells are of essentially the same character as those found in 

 the filaments of the recent Blue-green Algse. 



Genotype. — Camasia spongiosa, new species. 



Stratigraphic range. — Lower portion of Xewland limestone. 



Geographic distribution. — Eastern slope of Big Belt Mountains, 

 Montana. 



Observations. — As far as now known this species is represented 

 by one species that forms layers varying in thickness and extent. 

 The largest specimen in the collection has a thickness of 7 cm., with 

 a length of 21 cm. It is apparently a fragment of a large mass that 

 extended over a much larger area. 



The microscopic cells illustrated on plate 20 were obtained by 

 treating the specimen with hydrochloric acid and examining the 

 residual matter. All of the chains of cells thus far seen occur in 

 thin opal-like plates such as are found abundantly in the recent 

 calcareous lake deposits formed by Blue-green Alg?e. 



The only species yet referred to the genus is Camasia spongiosa. 



CAMASIA SPONGIOSA, new species 

 Plate 9, figs. I, 2; plate 12, figs, i, 2; plate 20, figs. 2-6, 6a 



The general form of this species is shown by the illustrations on 

 plates 9 and 12. It resembles in some respects the recent growth 

 deposited by Blue-green Algas as represented by figure 4 on plate 4. 



It evidently grew in extended masses on the bottom. The few 

 specimens in the collection are only fragments, and none of them 

 show indications of having come from near the outer margin of the 

 mass of which they formed a part. 



The microscopic structure is referred to on page 103 and illus- 

 trated on plate 20, figures -2-6. 



