EOZOON CAXADENSE AT COTE ST. PIERRE. 71 



not noticed by previous observers, is the occurrence of layers filled 

 with little globose casts of chamberlets, single or attached in groups, 

 and often exactly resembling the casts of Globigerince in greensand 

 (PL X. figs. 4-10). On weathered surfaces they were often especially 

 striking when examined with the lens. In some cases the chamberlets 

 seem to have been merely lined with serpentine, so that they weather 

 into hollow shells. The walls of these chamberlets have had the same 

 tubulated structure as Eozoon (fig. 4) ; so that they are in their essen- 

 tial characters minute acervuline specimens of that species, and similar 

 to those which I described in my paper of 1867* as occurring in the 

 limestones of Long Lake and Wentworth, and also in the loganite 

 filling the chambers of specimens of Eozoon from Burgess. Some of 

 them are connected with each other by necks or processes, in the 

 manner of the groups of chamberlets described by Griimbel as occur- 

 ring in a limestone from Finland, examined by him. That they are 

 organic I cannot doubt, and also that they have been distributed by 

 currents over the surface of the layers along with fragments of 

 Eozoon. Whether they are connected with that fossil or are speci- 

 fically distinct may admit of more doubt. They may be merely 

 minute portions detached from the acervuline surface of Eozoon, 

 and possibly of the nature of reproductive buds. On the other 

 hand, they may be distinct organisms growing in the manner of 

 Globigerina. As this is at present uncertain, and as it is convenient 

 to have some name for them, I propose to term them ArcJueosphce- 

 7'ince, understanding by that name minute Foraminiferal organisms, 

 having the form and mode of aggregation of Globigerina, but with 

 the proper wall of Eozoon. 



In slicing one of my specimens from Cote St. Pierre I have 

 recently observed a very interesting peculiarity of structure, which 

 deserves mention. It is an abnormal thickening of the calcareous 

 wall in patches extending across the thickness of four or five 

 lamellae, the latter becoming slightly bent in approaching the 

 thickened portion. This thickened portion is traversed by regu- 

 larly placed parallel canals of large size, filled with dolomite, while 

 the intervening calcite presents a very fine dendritic tubulation. 

 The longitudinal axes of the canals lie nearly in the plane of 

 the adjacent laminae. This structure reminds an observer of the 

 Ccenostroma type of Stromatopora, and may be either an abnormal 

 growth of Eozoon, consequent on some injury, or a parasitic mass of 

 some Stromatoporoid organism finally overgrown by the Eozoon. 

 The structure of the dolomite shows that it first incrusted the 

 interior of the canals, and subsequently filled them — an appearance 

 which I have also observed in some of the larger canals filled with 

 serpentine, and which is very instructive as to their true nature. 



From the above facts the true nature of Eozoon may, I think, be 

 rendered evident to any geologist, however little he may have made 

 the fossil Foraminifera a subject of study. The theories as to its 

 origin may be summed up thus : — 



1. The complicated theory of pseudomorphism and replacement, 

 * Quart. Journ. Geol. Soc. vol. xxiii. p. 260. 



