74 J. \Y. DAWSON ON THE OCCURRENCE OF 



chambers are in the lower part regularly laminated ; but they are 

 remarkable for their finely mammillated appearance, arising from 

 their division into innumerable connected chamberlets resembling 

 those of Archceosphcerina (fig. 4). In the upper part the structure be- 

 comes acervuline, and the chamberlets rise into irregular prominences, 

 which in the recent state must have been extremely friable, and, if 

 broken up and scattered over the surfaces of beds, would not be 

 distinguishable from the ordinary ArcJiceosphcerince. This specimen 

 thus gives further probability to the view that the Archceosplicerinai 

 may be for the most part detached chamberlets of Eozoon, perhaps 

 dispersed in a living state and capable of acting as germs.] 



EXPLANATION OF PLATE X. 



Fig. 1. Fragments of skeleton of Eozoon, imbedded in dolomite limestone, 

 (a) Fragment with canals, (b) Fragments not showing canals, (c) 

 Dolomite. (Magnified 10 diameters.) 



2. Laminated Eozoon. with vein of elirysotile. (a) Calcareous wall, slightly 



eroded with acid, (b) Serpentine filling chambers, (c) Chrysotile 

 vein crossing the structures. (10 diam.) 



3. Portion of a specimens imilar to that in fig. 2 ; a very thin slice more 



highly magnified, (a) Intermediate skeleton with portions of two 

 large canals, (a') Proper wall with fine tubulation. (b) Serpentine 

 filling chambers, (c) Chrysotile vein traversing serpentine. (Magnified 

 90 diam.) 



4. Small Archceosphcprina, showing tubulated wall. (200 diam.) 



5. 6, 7, 8. Archceosphcerina, casts, as opaque objects, of some of the varieties. 



(7."> diam.) 

 and 10. Similar specimens seen in section. (75 diam.) 



The specimen represented in fig. 4 is from Long Lake ; all the others are 

 from Petite Nation. 



Discussion. 



Prof. Duncan said that he thought the author had run the mine- 

 ralogists rather hard. For his own part, when he first examined 

 specimens of Eozoon he had come to the conclusion that they were 

 ancient Foraniinifera with Nummuline peculiarities ; and since he 

 had acquired a more intimate acquaintance with fibrous minerals 

 and serpentines, he found himself more than ever confirmed in this 

 view. The discovery of isolated masses was very interesting, seeing 

 that, whether they were separated fragments or distinct organisms, 

 they still showed the Nummuline structure. Prof. Duncan com- 

 pared the habit of growth of Eozoon to that of the Nullipores, and 

 suggested that it would be more philosophical to refer both the 

 latter and the Foraminifera to Hiickel's group " Protista." 



Mr. Etheridge remarked upon the singular fact that whilst, as 

 a general rule, we were disappointed in obtaining instructive sec- 

 tions of Eozoon, we had only to go to Dr. Carpenter to see sections 

 which seemed to be convincing. He thought the difference of 

 opinion that prevailed as to the nature of Eozoon was due mainly to 

 the difficulty that certainly existed of procuring specimens to show 

 the so-called tubuli and stolons. He stated that he had received 

 from Jersey specimens which at the first glance he said were like 



