﻿SALTER 
  BUDLE1GH 
  SALTERTON 
  FOSSILS. 
  297 
  

  

  11. 
  Rhynchonella, 
  sp. 
  PL 
  XYII. 
  fig. 
  14. 
  

  

  A 
  remarkable 
  fossil, 
  which, 
  if 
  it 
  were 
  more 
  perfect, 
  should 
  receive 
  

   a 
  name. 
  It 
  is 
  singularly 
  inflated, 
  both 
  on 
  the 
  sides 
  and 
  in^ 
  the 
  

   great 
  dorsal 
  fold, 
  which 
  occupies 
  one-half 
  of 
  the 
  width, 
  and 
  is 
  -y^ths 
  

   of 
  an 
  inch 
  long, 
  and 
  scarcely 
  so 
  wide, 
  while 
  the 
  depth 
  of 
  the 
  single 
  

   dorsal 
  valve 
  we 
  possess 
  is 
  y^ths. 
  The 
  shape 
  is 
  broad-ovate, 
  the 
  

   beak 
  much 
  pointed 
  and 
  rather 
  produced, 
  the 
  sides 
  arched, 
  inflated, 
  

   and 
  separated 
  by 
  a 
  rather 
  broad 
  depressed 
  space 
  from 
  the 
  raised 
  

   sinus, 
  which 
  has 
  four 
  strong 
  plaits. 
  The 
  sides 
  are 
  only 
  faintly 
  ribbed. 
  

   The 
  front 
  is 
  strongly 
  incurved. 
  

  

  The 
  hinge-teeth 
  diverge 
  widely 
  at 
  120°, 
  and 
  are 
  broad 
  and 
  thick 
  

   for 
  the 
  genus. 
  

  

  ), 
  ^ 
  LAMELLIBRANCHIATA. 
  

  

  1. 
  Modiolopsis 
  Armorici, 
  sp. 
  nov. 
  PI. 
  XVI. 
  figs. 
  1, 
  1 
  a. 
  

  

  This 
  large 
  and 
  fine 
  shell 
  is 
  particularly 
  abundant 
  in 
  the 
  pebble- 
  

   bed 
  ; 
  it 
  is 
  an 
  excellent 
  example 
  of 
  the 
  Silurian 
  Modiolopsis, 
  a 
  genus 
  

   conveniently 
  enough 
  separated 
  from 
  the 
  living 
  Modiola, 
  while 
  it 
  is 
  

   not 
  easy 
  to 
  find 
  absolute 
  characters 
  for 
  it. 
  The 
  stronger 
  anterior 
  

   muscle 
  is 
  a 
  good 
  general 
  mark, 
  and 
  the 
  form 
  of 
  the 
  shell 
  is 
  usually 
  

   much 
  rounder 
  than 
  in 
  the 
  modern 
  genus. 
  It 
  is 
  identical 
  with 
  a 
  

   species 
  common 
  in 
  the 
  May 
  Sandstone 
  of 
  Caen. 
  

  

  About 
  2 
  inches 
  wide, 
  1 
  J 
  inch 
  in 
  height, 
  and 
  with 
  the 
  united 
  valves 
  

   |ths 
  of 
  an 
  inch 
  thick. 
  The 
  shape 
  is 
  transverse-oval, 
  a 
  good 
  deal 
  

   broader 
  behind 
  than 
  at 
  the 
  beaks, 
  which 
  are 
  very 
  slightly 
  prominent, 
  

   and 
  lie 
  at 
  the 
  anterior 
  fifth. 
  From 
  thence 
  to 
  the 
  posterior 
  angle 
  

   runs 
  a 
  regular 
  convexity, 
  not 
  separated 
  by 
  any 
  defined 
  sinus 
  from 
  

   the 
  flatter 
  anterior 
  slope. 
  The 
  beak 
  is 
  not 
  very 
  convex. 
  Anterior 
  

   margin 
  strictly 
  rounded. 
  Posterior 
  margin 
  also 
  rounded, 
  the 
  pos- 
  

   terior 
  slope 
  not 
  much 
  flattened, 
  and 
  its 
  cardinal 
  angle 
  obtuse. 
  The 
  

   whole 
  shell 
  covered 
  by 
  concentric 
  lines 
  of 
  growth, 
  interrupted 
  in 
  the 
  

   outer 
  half 
  of 
  the 
  full-grown 
  shell 
  by 
  several 
  distinct 
  sharp 
  rugse, 
  

   placed 
  equally 
  apart 
  from 
  one 
  another. 
  These 
  ridges 
  or 
  varices 
  do 
  

   not 
  imbricate, 
  but 
  lie 
  at 
  the 
  same 
  level 
  of 
  the 
  shell. 
  

  

  A 
  transverse 
  variety, 
  with 
  less 
  conspicuous 
  ridges 
  and 
  closer 
  lines 
  

   of 
  growth, 
  may 
  be 
  a 
  distinct 
  species. 
  We 
  have 
  not 
  room 
  to 
  figure 
  it, 
  

  

  2. 
  Modiolopsis 
  lirattts, 
  sp. 
  nov. 
  PI. 
  XVI. 
  fig. 
  4. 
  

  

  Transverse 
  - 
  ovate 
  ; 
  length 
  1| 
  inch; 
  height 
  13 
  lines 
  ; 
  depth 
  of 
  united 
  

   valves 
  8 
  lines. 
  Anterior 
  side 
  produced, 
  rather 
  narrow, 
  rounded. 
  Beak 
  

   at 
  the 
  anterior 
  fourth. 
  Posterior 
  margin 
  somewhat 
  obliquely 
  trun- 
  

   cated 
  above, 
  the 
  angle 
  rounded 
  off; 
  no 
  sinus. 
  

  

  Whole 
  surface 
  concentrically 
  striate, 
  but 
  not 
  closely 
  so, 
  passing 
  on 
  

   the 
  anterior 
  side 
  into 
  close-set 
  wrinkles 
  tolerably 
  equal 
  in 
  size 
  over 
  

   the 
  anterior 
  portion 
  from 
  beneath 
  the 
  beak 
  forwards. 
  

  

  We 
  have 
  only 
  one 
  valve. 
  It 
  is 
  a 
  narrower 
  species 
  than 
  the 
  last, 
  

   and 
  the 
  close 
  wrinkling 
  of 
  the 
  front 
  is 
  a 
  good 
  character. 
  This 
  also 
  

   occurs 
  in 
  the 
  May 
  Sandstone 
  of 
  France 
  (De 
  Verneuil, 
  in 
  Uteris). 
  

  

  x2 
  

  

  