100  PRE-CAMBRIAN    GEOLOGY   OF    NORTH    AMERICA. 
The  Aspidella  of  the  Momable  slates  is  probably  of  organic  origin, 
but  it  may  be  questioned.  Other  reported  forms  are  inaccessible  for 
study. 
In  the  Lake  Superior  country  markings  have  been  reported  as 
found  in  the  Huronian  iron  formation  of  the  Menominee  iron  district 
of  Michigan.  An  examination  of  the  specimens  indicates  that  they 
probably  are  from  the  basal  detrital  material  of  the  Cambrian  which 
rests  upon  the  Huronian  iron  formation.  In  the  Animikie  rocks  of 
the  Lake  Superior  region  the  evidence  of  life  consists  of  the  presence 
of  graphitic  material  in  the  slates  and  of  a  supposed  fossil  mentioned 
by  G.  F.  Matthew.  In  the  Minnesota  quartzite  of  the  upper  Huron- 
ian series  lingula-like  forms  and  an  obscure  trilobitic-looking  impres- 
sion are  described  by  Winchell.  The  latter  has  been  examined  and 
the  conclusion  is  reached  that  it  is  of  inorganic  origin.  As  to  the 
lingula  forms,  the  weight  of  evidence  is  in  favor  of  their  being  small 
flattened  concretions. 
In  general,  the  reported  discoveries  of  fossils  in  the  crystalline 
rocks  of  the  Algonkian  are  as  yet  too  problematic  to  be  of  value  to 
the  geologist  and  paleontologist.  Apparently  the  best  that  can  be 
said  of  Eozoon  and  allied  forms  is  that  they  may  be  of  organic  origin, 
but  it  is  not  yet  proved.  The  same  appears  to  be  true  of  the  supposed 
fossil  sponges  described  by  G.  F.  Matthew  from  the  Laurentian  rocks 
of  New  Brunswick.  The  graphite  in  pre-Cambrian  forms  is  prob- 
ably in  many  cases  of  organic  origin,  but  of  the  character  of  the  life 
we  know  nothing. 
Palaotrochis,  formerly  referred  to  as  a  pre-Paleozoic  coral,  is  de- 
termined by  J.  A.  Llolmes  and  J.  S.  Diller  as  of  inorganic  origin. 
Ells,33  in  1899,  gives  a  historical  account  of  the  geological  nomen- 
clature of  that  part  of  Canada  which  extends  roughly  from  the  Red 
River  of  Manitoba  eastward  over  Canada.  The  present  usage  with 
reference  to  pre-Cambrian  rocks  may  only  be  mentioned. 
In  Nova  Scotia  the  term  pre-Cambrian  has  been  given  to  certain 
old  crystalline  rocks  which  were  found  to  underlie  the  recognized 
Cambrian  of  the  coast  or  of  the  gold  series,  and  which  were  found  to 
strongly  resemble  certain  portions  of  the  Laurentian  or  Huronian 
of  the  western  provinces. 
In  New  Brunswick  there  has  been  little  change  in  the  nomenclature 
proposed  by  Matthew,  Bailey,  and  Hunt.  The  lowest  division  of  the 
crystalline  rocks  was  held  to  conform  most  closely  in  its  details  to  the 
Laurentian  of  the  Canadian  Survey,  This  series  was  divided  into  a 
lower  and  an  upper  division,  the  former  of  which  was  regarded  as  the 
equivalent  of  the  lower  or  Fundamental  gneiss  of  the  Ottawa  district, 
while  the  latter  was  supposed  to  represent  the  limestone  and  gneiss  of 
the  Grenville  series  of  Quebec.  The  Huronian  was  made  to  include 
three  divisions,  viz,  the  Colebrook,  the  Kingston,  and  the  Coastal, 
