74 RELICS OF PRIMEVAL LIFE 



porae " or layer-corals of the lower Palaeozoic rocks 

 next in succession to the Laurentian and Huronian ; 

 the forms were similar in all the specimens, while 

 the mineralizing substances were different ; they 

 were found only in the limestone, and specially in 

 one of the three great beds known in the formation, 

 the upper limestone of the Grenville system. He 

 exhibited specimens, and mentioned these probabili- 

 ties at the meeting of the American Association in 

 1859. In 1862 it was suggested to Logan that the 

 microscopic structure of some of the best preserved 

 examples should be studied, and slices were accord- 

 ingly prepared and submitted to the writer for 

 examination. They revealed in the calcareous 

 laminae of the specimens complicated systems of 

 canals or tubes filled with mineral matter, which 

 appeared to be similar to those that Carpenter had 

 recognised in the thickened parts of the shells of 

 modern Foraminifera. This clew being followed, 

 large numbers of slices of the supposed fossils and of 

 the containing limestone and of similar limestones 

 from other parts of the world were examined. 



The writer also visited the localities of " Eozoon," 

 and studied its mode of occurrence in sihi. The 

 facts ascertained were communicated to the Geo- 



