204 0. HoUedahl — Structures like Walcott's 



plane and quite parallel. This lamination is, however, 

 of another type than the more coarse irregular one which 

 is seen in the lower part of the same specimen. This 

 exceedingly fine lamination seems, to judge from the 

 pieces at hand, to be secondary in relation to the coarser 

 one. A similar lamination can also be observed in figure 

 6, cutting through the coarser structure. A fine lamina- 

 tion that might correspond to the one seen in my figure 

 6 seems also to cross the coarser structure of the Newlan- 

 dia frondosa in the specimen depicted in Walcott^s plate 

 6, figure 3. This lamination probably corresponds to the 

 ^^bands" of Abbott (1900), which, as he says, ^^run 

 across the beds at various angles." He states further that 

 ''the rods invariably start from the last-mentioned bands, 

 and may be seen at every angle. ' ' 



The regular, ''basaltic" tubes, the Greysonia structure, 

 thus are connected with one type of lamination, the more 

 irregular radiating rods or indications of rods of the 

 Netvlaudia structure with another, and as both types of 

 laminae are seen crossing each other, they can not well 

 both represent a primary structure, coming into existence 

 at the time of deposition. Even without this crossing, 

 one would judge that a structure like that sho^\m in figure 

 4 is too geometrically regular to have anything to do with 

 organic deposition. Walcott also remarks (p. 109) 

 concerning the Greysonia that "it is difficult to conceive 

 of the tubular structure of Greysonia as a deposit made 

 by algae, but with the example of the varied forms of 

 recent deposits made by the blue-green algae (Cyanophy- 

 ceae) and the other fossil forms described in this paper 

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



As far as can be judged from my specimens, the 

 coarser Neivlandia structure cannot be of organic origin. 

 An individual like the one in figure 3 shows so great a 

 regularity that only one of two conclusions can be drawn : 

 either it represents a true organic skeleton, like that of a 

 huge Nummulites or Receptaculites, or it must be wholly 

 of inorganic origin. The recent ' ' lake balls ' ^ that Walcott 

 figures have no regular radiating structure at all, nor 

 should such a structure be expected in a deposit of that 

 character. That we have a true skeleton no one assumes ; 

 on the other hand, the regular spherical laminae of figure 

 3 may in other specimens be quite irregularly undulating, 

 as in figure 6, or practically straight, as in figure 5, lower 

 part. To judge from the specimens figured, without 

 taking into account the general view of the structures in 



