﻿210 Canadian Record of Science. ^ 



This curious fossil was described with some other Carbon- 

 iferous forms in the Report of the Peter Eedpatli Museum 

 for 1883, and as that publication is not very generally 

 accessible, the description may be repeated here : — 



Megastroiiia laiiiinosum, Dawson. 



*' Broadly expanded layers about one millimetre in thick- 

 ness, and two millimetres or more apart. Each layer 

 consists of a double membrane, beset with numerous spi- 

 cules pointing inwards and looking like two brushes facing- 

 each other. The membranes are penetrated by openings 

 or oscula, and appear to be porous or reticulate in their 

 substance and to have cellular thickeuings in places, 

 giving them a netted appearance. The layers sometimes 

 though rarely unite, and are not always continuous when 

 seen in section ; tliis appearance being perhaps produced 

 by large openings or spaces. In each layer the ends of 

 the opposing spicules are sometimes in contact, sometimes 

 separated by a space, empty or filled with calcite. The 

 intervals between the layers are occupied by organic lime- 

 stone, consisting of small shells and fragments of shells 

 and corals. As many as twelve or thirteen layers are 

 sometimes superimposed, and their horizontal extent 

 seems to amount to a foot or more. The layers have a 

 deep brown colour, wliile the enclosing limestone is of a 

 light gray tint. 



''■ This remarkable body was found in the fossiliferous 

 limestone of Brookfield, in patches parallel with the 

 stratification, and at first sight resembled a coarse Stjoma- 

 topora. When sliced and examined under the microscope, 

 it presents the appearance above described. The mem- 

 branes referred to, from their deep brown color, would 

 seem to have been of a horny or chitinous character. They 

 are sometimes Ijent and folded, as if by pressure, and 

 ap])ear to have been of a flexible and tough consistencv. 



