﻿94 
  Twenty-eighth 
  Eepokt 
  on 
  the 
  State 
  Museum. 
  

  

  vertically 
  by 
  strong 
  radiating 
  striae, 
  extending 
  from 
  near 
  

   the 
  apex 
  to 
  the 
  margin; 
  shorter 
  interstitial 
  strise 
  alternate 
  

   near 
  the 
  margin. 
  

  

  The 
  shell 
  was 
  thin 
  and 
  readily 
  distorted 
  by 
  pressure. 
  Of 
  

   seven 
  entire 
  individuals, 
  two 
  only 
  appear 
  to 
  be 
  in 
  a 
  normal 
  

   condition 
  ; 
  the 
  others 
  are 
  compressed, 
  so 
  that 
  the 
  apex 
  of 
  each 
  

   is 
  placed 
  in 
  a 
  different 
  position, 
  with 
  relation 
  to 
  any 
  given 
  

   portion 
  of 
  the 
  margin. 
  

  

  Formation 
  and 
  locality. 
  — 
  Trenton 
  Limestone, 
  upper 
  third, 
  

   Trenton 
  Falls, 
  N. 
  Y. 
  

  

  CONCHOPELTIS 
  MlNOTSSOTENSIS 
  n. 
  Sp. 
  

  

  Shell 
  obtusely 
  conical 
  ; 
  base 
  slightly 
  elliptical 
  ; 
  apex 
  

   excentric, 
  variable 
  in 
  different 
  individuals 
  ; 
  height 
  one-half 
  

   the 
  greatest 
  diameter. 
  Shallow 
  undulations 
  of 
  growth 
  occur 
  

   one-half 
  the 
  distance 
  to 
  the 
  apex, 
  finer-rlines 
  near 
  the 
  margin. 
  

   Substance 
  of 
  shell 
  not 
  preserved. 
  

  

  The 
  casts 
  preserving 
  the 
  lines 
  of 
  growth 
  indicate 
  the 
  same 
  

   character 
  of 
  shell 
  as 
  that 
  of 
  G. 
  alternata, 
  from 
  the 
  Trenton 
  

   Limestone 
  of 
  New 
  York. 
  

  

  Formation 
  and 
  locality. 
  — 
  Trenton 
  Limestone, 
  four 
  miles 
  

   below 
  Medford, 
  Canon 
  River, 
  Minn. 
  

  

  BATHYURUS 
  Billings* 
  

  

  BATHYURUS 
  LOISTGISPINUS 
  U. 
  Sp. 
  

  

  General 
  outline 
  oval, 
  strongly 
  convex. 
  Head 
  semicircular, 
  

   convex; 
  width 
  twice 
  the 
  length, 
  margin 
  broad, 
  slightly 
  con- 
  

  

  *As 
  specimens 
  of 
  different 
  species 
  of 
  Bathyurus, 
  present 
  characters 
  of 
  the 
  genus 
  

   Bathyurellus 
  Billings, 
  and 
  Asaphiscus 
  Meek, 
  a 
  comparison 
  of 
  the 
  three 
  genera 
  has 
  led 
  

   me 
  to 
  the 
  conclusion, 
  that 
  Bathyurellus 
  and 
  Asaphiscus 
  have 
  been 
  separated 
  from 
  

   Bathyurus 
  on 
  specific, 
  rather 
  than 
  generic 
  differences. 
  Professor 
  Billings 
  gives, 
  as 
  the 
  

   generic 
  difference 
  of 
  Bathyurus 
  and 
  Bathyurellus, 
  that 
  the 
  former, 
  as 
  represented 
  

   by 
  the 
  typical 
  species 
  B. 
  extans 
  Hall, 
  B. 
  Nero 
  and 
  B. 
  Cybele 
  Billings, 
  has 
  a 
  subcylindrical 
  

   glabella, 
  rounded 
  in 
  front, 
  strongly 
  convex 
  and 
  with 
  obscure 
  glabellar 
  furrows 
  ; 
  while 
  

   in 
  the 
  latter 
  the 
  glabella 
  is 
  conical 
  or 
  pointed 
  in 
  front 
  and 
  exhibits 
  no 
  traces 
  of 
  glabellar 
  

   furrows 
  ; 
  the 
  pygidium 
  also, 
  differs 
  in 
  not 
  being 
  strongly 
  convex, 
  in 
  having 
  a 
  shorter 
  axis, 
  

   and, 
  in 
  general, 
  a 
  wider 
  border. 
  Professor 
  Meek 
  gives, 
  as 
  the 
  generic 
  differences 
  of 
  

   Asaphiscus 
  and 
  Bathyurellus, 
  the 
  decidedly 
  depressed 
  conical 
  glabella, 
  the 
  margin 
  of 
  

   the 
  head, 
  first 
  convex 
  and 
  sloping 
  forward 
  into 
  a 
  deep, 
  transverse, 
  mesial 
  furrow, 
  then 
  

   rising 
  in 
  the 
  form 
  of 
  a 
  convex 
  margin 
  to 
  the 
  front, 
  the 
  mesial 
  lobe 
  of 
  the 
  pygidium 
  

   being 
  also 
  proportionally 
  longer, 
  and 
  the 
  free 
  margins 
  of 
  the 
  same 
  much 
  narrower, 
  and 
  

   less 
  flattened 
  and 
  alate. 
  Bathyurellus 
  can 
  hardly 
  claim 
  the 
  title 
  of 
  subgenus, 
  as 
  given 
  

   by 
  Its 
  author. 
  The 
  presence 
  of 
  faint 
  glabellar 
  furrows, 
  conical 
  glabella, 
  grooved 
  pleura, 
  

   nine 
  thoracic 
  segments, 
  and 
  pygidium 
  of 
  the 
  same 
  character 
  in 
  all 
  essential 
  particulars, 
  

   clearly 
  indicates, 
  according 
  to 
  the 
  description 
  of 
  the 
  author, 
  that 
  Asaphiscus 
  is 
  not 
  to 
  

   be 
  separated 
  from 
  Bathyurus 
  by 
  generic 
  characters. 
  

  

  