﻿Vol. 
  53.] 
  FOSSILS 
  FROM 
  THE 
  MORTE 
  SLATES, 
  ETC. 
  449 
  

  

  Avictjlopecten 
  3ITJNDUS, 
  sp. 
  nov. 
  (PI. 
  XXXIII. 
  figs. 
  14, 
  14 
  a, 
  15 
  & 
  

   15 
  a.) 
  

  

  Locality. 
  Oakhampton 
  Quarry. 
  Two 
  good, 
  and 
  some 
  imperfect, 
  

   specimens. 
  

  

  Size. 
  Height 
  25 
  mm., 
  length 
  32 
  mm. 
  

  

  Description. 
  Left 
  valve 
  moderate 
  in 
  size, 
  slightly 
  transverse, 
  

   obliquely 
  oval. 
  Umbo 
  situate 
  at 
  or 
  about 
  the 
  anterior 
  third 
  of 
  

   the 
  length, 
  acute, 
  slightly 
  surpassing 
  the 
  hinge-line 
  and 
  tending 
  

   slightly 
  forward. 
  Anterior 
  wing 
  long, 
  narrow, 
  triangular, 
  acutely 
  

   pointed, 
  and 
  extending 
  beyond 
  the 
  front 
  of 
  the 
  body. 
  Posterior 
  

   wing 
  (very 
  indistinctly 
  seen) 
  apparently 
  nearly 
  similar 
  in 
  shape, 
  

   but 
  rather 
  larger. 
  Margins 
  arching 
  in 
  a 
  continuous 
  curve, 
  which 
  

   is 
  deepest 
  rearward. 
  Surface 
  with 
  40 
  or 
  50 
  narrow 
  subacute 
  

   ribs, 
  sometimes 
  alternating, 
  separated 
  by 
  rather 
  wider 
  concave 
  

   furrows 
  ; 
  the 
  whole 
  crossed 
  by 
  extremely 
  regular, 
  close, 
  sharp, 
  

   minute 
  threads, 
  which 
  seem 
  to 
  undulate 
  so 
  as 
  to 
  be 
  slightly 
  convex 
  

   to 
  the 
  beak 
  on 
  the 
  ribs, 
  and 
  concave 
  on 
  the 
  furrows. 
  

  

  Remarks. 
  This 
  species 
  is 
  very 
  similar 
  to 
  A. 
  gracilis, 
  Beushausen, 
  1 
  

   but 
  that 
  species 
  is 
  more 
  oblique, 
  its 
  hind 
  wing 
  is 
  shorter 
  and 
  of 
  a 
  

   different 
  shape, 
  and 
  the 
  transverse 
  marks 
  are 
  described 
  as 
  irregular. 
  

   A. 
  perovalis, 
  Beushausen, 
  2 
  is 
  less 
  oblique, 
  and 
  has 
  a 
  much 
  shorter 
  

   hinge-line. 
  A. 
  Wulfi, 
  Freeh, 
  3 
  is 
  very 
  similar 
  in 
  shape 
  and 
  orna- 
  

   ment, 
  except 
  that 
  its 
  umbo 
  seems 
  blunter 
  and 
  more 
  central, 
  its 
  

   anterior 
  notch 
  shallower, 
  its 
  front 
  wing 
  broader, 
  and 
  its 
  hind 
  wing 
  

   apparently 
  much 
  larger, 
  bringing 
  it 
  within 
  the 
  section 
  Pterino- 
  

   pecten 
  ; 
  both 
  in 
  Freeh's 
  figures 
  and 
  our 
  specimens, 
  however, 
  the 
  

   hind 
  wings 
  are 
  badly 
  preserved. 
  It 
  seems 
  to 
  me 
  that 
  our 
  shell 
  

   cannot 
  be 
  identified 
  with 
  either 
  of 
  these 
  three 
  Lower 
  Devonian 
  

   species, 
  though 
  standing 
  midway 
  between 
  the 
  first 
  and 
  the 
  last. 
  

  

  Avicula 
  Neptuni, 
  Goldfuss, 
  4 
  is 
  also 
  similar, 
  but 
  has 
  less 
  acute 
  ears, 
  

   coarser 
  transverse 
  strise, 
  and 
  apparently 
  a 
  longer 
  hinge-line. 
  

  

  LlMOPTERA 
  SEMIRADIATA, 
  Freeh. 
  (PI. 
  XXXIV. 
  figs. 
  1, 
  la, 
  2 
  & 
  

  

  2 
  a.) 
  

  

  1889. 
  Pterinea 
  aff. 
  lineata, 
  Kayser, 
  Abli. 
  k. 
  Preuss. 
  geol. 
  Landesanst., 
  n. 
  s., 
  pt. 
  i. 
  

   p. 
  21 
  & 
  pi. 
  viii. 
  fig. 
  2. 
  

  

  1891. 
  Limoptera 
  semiradiata, 
  Freeh, 
  Abh. 
  geol. 
  Specialk. 
  Preuss. 
  vol. 
  ix. 
  pt. 
  iii. 
  

   p. 
  65 
  & 
  pi. 
  v. 
  figs. 
  1-3, 
  5-8. 
  

  

  Locality. 
  Oakhampton. 
  Two 
  specimens. 
  

  

  Size. 
  Length 
  and 
  height, 
  about 
  40 
  mm. 
  

  

  These 
  obscure 
  specimens, 
  one 
  of 
  which 
  is 
  much 
  crushed 
  and 
  the 
  

  

  1 
  1884. 
  Beushausen, 
  Abh. 
  geol. 
  Specialk. 
  Preuss. 
  vol. 
  vi. 
  pt. 
  i. 
  p. 
  54 
  & 
  pi. 
  ii. 
  

   fig. 
  5. 
  

  

  2 
  Ibid. 
  p. 
  53 
  & 
  pi. 
  ii. 
  fig. 
  6. 
  

  

  3 
  1891. 
  Freeh, 
  Abh. 
  geol. 
  Specialk. 
  Preuss. 
  vol. 
  ix. 
  pt. 
  iii. 
  p. 
  25 
  & 
  pi. 
  if. 
  

   fig. 
  7. 
  

  

  4 
  1834-40. 
  Goldfuss, 
  • 
  Petref. 
  Germ.' 
  vol. 
  ii. 
  p. 
  125 
  & 
  pi. 
  cxvi. 
  fig. 
  4. 
  

  

  Q. 
  J. 
  G. 
  S. 
  No. 
  211. 
  2 
  h 
  

  

  