158 



ARCHAEAN TIME. 



there were Lichens over the bare rocks. The easily destructible 

 Fungi may also have lived in damp places. 



2. Animals. — Animals of the lowest division of animal life, that of 

 Rhizopods among Protozoans, were probably abundant. The existence 

 of strata of limestone, alternating with metamorphic schists, affords a 

 strong presumption in favor of the existence of some living species, since 

 all newer limestones of much extent intercalated among stratified rocks 

 have been made mainly of the calcareous relics of such species ; and 

 the Rhizopods are those animals which should have first appeared. 

 These limestones may, however, have proceeded from the secretions 

 of these plants, kinds related to Nullipores and Coccoliths (pp. 60, 

 135). The apatite (calcium phosphate), which is abundant in some 

 Archaean rocks, especially the limestones, has been supposed to have 

 come from animal secretions (pp. 60, 61) ; but it may be a deposit 

 from the sea-water, or from preexisting rocks. 



The existence of Rhizopods is believed by many to have been dem- 

 onstrated by the discovery of their fossils in serpentine associated 

 with the limestone, and later in the limestone itself. Dawson, who 

 made the earliest investigations of them, named the species (one found 



in Canada) Eozoon Canadense. It is pro- 

 nounced a kind of coral-making Rhizopod. 

 The coral-like masses attributed to them 

 are sometimes several feet in diameter. 



Fig. 214 represents, natural size, a sec- 

 tion of a specimen of this fossil, from 

 Grenville. The white bands are the cal- 

 careous layers supposed to have been se- 

 creted by a layer of the Rhizopods, while 

 the dark bands correspond in position to 

 the layer of Rhizopods, and are made up 

 of mineral material (serpentine generally, 

 sometimes pyroxene, loganite, etc., accord- 

 ing to Hunt) that, after the death of the 

 animals, filled the cells. Dilute muriatic 

 acid removes the limestone, and opens the rest to examination. 



The specimens of Eozoon were first supposed to be Polyp-corals (Logan's Hep. Geol. 

 Can., 1863, p. 48), and afterward announced as Rhizopods by Dr. Dawson (Logan's 

 Rep. Geol. Canada, for 1866; Am. J. Sci., II. xxxvii. 272, 431, 1864, xl. 344, 1865). 



They occur in the third or Grenville stratum of limestone of the Laurentian, near 

 Grenville, and in the Petite Nation Seignory; also in Burgess (where the calcareous 

 part is dolomite according to Hunt), and at the Grand Calumet, in a limestone whose . 

 place in the series is not determined; but whether or not anywhere in the first and 

 second limestones is not known; also in Nova Scotia, in New Brunswick, and in 

 Massachusetts, at Newburyport, Chelmsford and Bolton, where the spaces are filled 





