70 LIFE ON THE EARTH. 



Gneiss and Mica Schist. No one is likely to believe 

 this however who attends seriously to the facts re- 

 garding the successive appearance of the classes, 

 orders, families, genera and species, as we search the 

 records of Geological time. 



EARLIEST SYSTEMS OF LIFE. 



The earliest system of life of which comments 

 remain is found in that very low part of the fossil- 

 iferous rocks of Wales, to which Professor Sedgwick 

 first directed attention, now called the Lingula Zone. 

 Perhaps the fossils of Bray, in the county of Wick- 

 low, may belong to an older group of the strata, but 

 this is assumed rather than proved. Of the two 

 generic forms there discovered, Oldhamia may be a 

 plant; Histioderma is an Annelid, probably of the 

 Cephalobranchiate order. Taking our stand on the 

 now well-explored Lingula Zone, but including in 

 our Survey the forms just mentioned, we find the 

 following characters of marine life, for no trace of 

 terrestrial or of Fresh-water organization has been 

 observed. 



Zoophyta 1 One genus. Oldhamia, 2 species. 

 Annelida 2 genera. Histioderma Arenicolites 



2 species. 



