﻿1864.] 
  SALTER 
  LINGULA-FLAG 
  FOSSILS. 
  237 
  

  

  doubt 
  about 
  the 
  genus. 
  The 
  small 
  eye 
  and 
  the 
  want 
  of 
  an 
  ocular 
  

   ridge 
  render 
  it 
  very 
  unlike 
  Conocoryphe. 
  In 
  some 
  respects 
  C. 
  

   variolaris 
  resembles 
  the 
  genus 
  Sao, 
  in 
  others 
  Arionellus, 
  and 
  I 
  think 
  

   it 
  unites 
  characters 
  found 
  in 
  both 
  these 
  genera. 
  But 
  as 
  there 
  is 
  a 
  

   distinct 
  front 
  margin, 
  and 
  as 
  the 
  glabella-lobes 
  are 
  like 
  those 
  of 
  

   several 
  species 
  of 
  Conocoryphe 
  (Conocephalus), 
  while 
  the 
  species 
  has 
  

   neither 
  the 
  large 
  eyes 
  of 
  Sao 
  nor 
  the 
  reduced 
  glabella 
  of 
  Arionellus, 
  

   I 
  prefer 
  to 
  leave 
  it 
  with 
  the 
  first-named 
  genus. 
  Barrande's 
  acuteness 
  

   has 
  not 
  missed 
  the 
  relation 
  which 
  really 
  subsists 
  between 
  two 
  genera 
  

   so 
  different 
  in 
  appearance 
  as 
  the 
  two 
  last 
  mentioned. 
  

   Locality, 
  Porth-y-Rhaw. 
  

  

  HoLOCEPHALINA, 
  gen. 
  nOV. 
  [CONOCEPHALID^.] 
  

  

  Gen. 
  Char. 
  — 
  Head 
  transverse, 
  semicircular, 
  with 
  a 
  very 
  small 
  

   and 
  obscure 
  glabella, 
  without 
  lobes, 
  with 
  wide 
  free 
  cheeks, 
  and 
  

   a 
  wide 
  front 
  margin. 
  The 
  facial 
  suture 
  and 
  the 
  eye 
  are 
  placed 
  at 
  

   almost 
  the 
  extreme 
  angle 
  of 
  the 
  head, 
  which 
  is 
  shortly 
  spinous. 
  

  

  There 
  are 
  nine 
  (or 
  more) 
  body-rings, 
  grooved 
  and 
  facetted. 
  

  

  TaH 
  ? 
  

  

  Distinct 
  from 
  all 
  the 
  genera 
  yet 
  described 
  by 
  its 
  form 
  and 
  the 
  ex- 
  

   treme 
  position 
  of 
  the 
  facial 
  sutures 
  and 
  eyes. 
  It 
  has, 
  however, 
  affi- 
  

   nities 
  with 
  Arionellus, 
  in 
  the 
  small 
  obscure 
  glabella 
  ; 
  and 
  that 
  genus 
  

   shows 
  a 
  strong 
  tendency 
  to 
  have 
  the 
  suture 
  marginal, 
  and 
  more 
  so 
  

   in 
  the 
  adult 
  than 
  in 
  the 
  young 
  state. 
  It 
  is 
  not, 
  however, 
  nearly 
  so 
  

   marginal 
  in 
  any 
  species 
  of 
  Arionellus 
  as 
  it 
  is 
  in 
  Holocephalina. 
  

  

  HOLOCEPHALLNA 
  PrIMORDIALIS. 
  PI. 
  XIII. 
  fig. 
  9. 
  

  

  This 
  species 
  is 
  less 
  than 
  an 
  inch 
  in 
  length 
  ; 
  and 
  as 
  at 
  present 
  only 
  

   a 
  single 
  specimen 
  has 
  been 
  observed, 
  the 
  characters 
  of 
  the 
  species 
  will 
  

   be 
  those 
  of 
  the 
  genus. 
  

  

  Locality, 
  Porth-y-Rhaw. 
  

  

  Agnosttts 
  princeps, 
  Salter. 
  PI. 
  XIII. 
  fig. 
  8. 
  Memoirs 
  Geol. 
  Survey, 
  

   vol. 
  iii. 
  (ined.) 
  pi. 
  5. 
  fig. 
  1. 
  

  

  This 
  species 
  will 
  be 
  figured 
  and 
  described 
  in 
  the 
  forthcoming 
  

   volume 
  of 
  the 
  Geological 
  Survey 
  Memoirs 
  on 
  North 
  Wales, 
  by 
  Prof. 
  

   Ramsay 
  and 
  myself. 
  

  

  Locality, 
  Porth-y-Rhaw. 
  Abundant. 
  

  

  Microdisctjs 
  punctatus, 
  spec. 
  nov. 
  PI. 
  XIII. 
  fig. 
  11. 
  

  

  Dr. 
  Emmons 
  described, 
  from 
  his 
  Taconic 
  strata 
  (see 
  ' 
  American 
  

   Geology/ 
  vol. 
  i. 
  p. 
  116. 
  pi. 
  1. 
  fig. 
  8), 
  a 
  minute 
  form, 
  which, 
  from 
  its 
  

   association 
  with 
  Graptolites 
  and 
  Mollusca, 
  Barrande 
  thinks 
  may 
  be 
  

   the 
  young 
  state 
  of 
  a 
  Trinucleus 
  or 
  some 
  such 
  Lower 
  Silurian 
  genus. 
  

   This 
  is 
  quite 
  possible. 
  But, 
  at 
  least, 
  Emmons's 
  figure 
  is 
  singularly 
  

   like 
  the 
  small 
  fossil 
  here 
  figured, 
  and 
  which 
  Mr. 
  Hicks 
  finds 
  abundant 
  

   in 
  the 
  lower 
  strata 
  of 
  the 
  section 
  at 
  Porth-y-Rhaw. 
  I 
  do 
  not 
  feel 
  

   inclined 
  to 
  institute 
  a 
  new 
  genus 
  for 
  this 
  while 
  there 
  is 
  a 
  probability 
  

   it 
  may 
  be 
  the 
  fry 
  of 
  some 
  larger 
  Trilobite. 
  The 
  characters 
  may 
  stand 
  

   thus 
  in 
  brief: 
  — 
  

  

  Head 
  without 
  eyes 
  or 
  facial 
  suture 
  ; 
  margined, 
  the 
  glabella 
  and 
  

  

  