﻿822 
  PROCEEDiyaS 
  OF 
  THE 
  NATIONAL 
  Ml 
  SEUM. 
  vouxx. 
  

  

  northern 
  K. 
  glacialis 
  (Leacli) 
  with 
  which 
  it 
  was 
  formerly 
  identified. 
  

   It 
  is 
  a 
  smaller, 
  shorter, 
  and 
  more 
  intiated 
  species, 
  with 
  a 
  shorter 
  and 
  

   more 
  sloping- 
  antero-dorsal 
  marofiu 
  and 
  a 
  more 
  evenly 
  curved 
  ventral 
  

   margin, 
  without 
  the 
  distinct 
  antero-veutral 
  indentation 
  seen 
  in 
  that 
  

   species. 
  The 
  convex 
  valve 
  lias 
  a 
  distinct, 
  posterior 
  radial 
  ridge 
  which 
  

   is 
  faint 
  or 
  lacking 
  in 
  K. 
  (flacialis. 
  There 
  are 
  also 
  ditferences 
  in 
  the 
  

   hinge, 
  in 
  the 
  right 
  valve 
  of 
  the 
  latter 
  the 
  teeth 
  are 
  more 
  divergent, 
  etc. 
  

   Doctor 
  Carpenter, 
  who 
  established 
  the 
  group 
  KennerUa, 
  defined 
  it 
  as 
  

   ditfering 
  from 
  typical 
  Tandorn 
  in 
  having 
  an 
  ossicle 
  on 
  the 
  cartilage 
  or 
  

   resilinm. 
  and 
  radial 
  grooves 
  on 
  the 
  right 
  valve. 
  Perhaps 
  the 
  simple 
  

   linear 
  form 
  of 
  the 
  resilinm 
  in 
  Kennerlia 
  and 
  its 
  forked 
  or 
  V-sliaped 
  

   form 
  in 
  true 
  Pandora 
  (type 
  P. 
  rostata 
  Lamarck) 
  maybe 
  of 
  more 
  impor- 
  

   tance. 
  The 
  intermediate 
  ridge 
  in 
  the 
  left 
  valve 
  of 
  Pandora 
  fits 
  between 
  

   the 
  two 
  divisions 
  of 
  the 
  V-shaped 
  resilinm. 
  There 
  is 
  also 
  in 
  Kennerlia 
  

   a 
  small, 
  buttress-like 
  projection 
  within 
  the 
  margin, 
  under 
  the 
  beak, 
  

   which 
  supports 
  an 
  inward 
  projecting 
  portion 
  t>f 
  the 
  ligament, 
  darker 
  

   in 
  color 
  than 
  the 
  resilinm. 
  

  

  Family 
  PERIPLOMID.F.. 
  

  

  PERIPLOMA 
  AFFINIS. 
  new 
  species. 
  

   (Plate 
  LXXXVII. 
  tig. 
  4.) 
  

  

  Shell 
  thin, 
  fragile, 
  broad 
  ovate, 
  with 
  the 
  beaks 
  behind 
  the 
  middle 
  

   and 
  with 
  a 
  short, 
  narrowed 
  posterior 
  end. 
  The 
  antero-dorsal 
  margin 
  

   is 
  broadly 
  convex: 
  anterior 
  end 
  nearly 
  evenly 
  rounded, 
  but 
  slightly 
  

   produced 
  in 
  the 
  middle; 
  ventral 
  margin 
  evenly 
  convex 
  to 
  the 
  base 
  of 
  

   the 
  rostral 
  region 
  where 
  it 
  becomes 
  slightly 
  incurved; 
  ])osterior 
  end 
  

   much 
  narrowed, 
  compressed 
  and 
  produced 
  into 
  a 
  short, 
  blunt 
  rostrum 
  

   with 
  the 
  edges 
  gaping 
  slightly 
  at 
  the 
  end: 
  postero-dorsal 
  margin 
  

   nearly 
  straight, 
  sloping 
  rapidly 
  to 
  tlie 
  angle 
  of 
  the 
  rostrum: 
  a 
  faint 
  

   diagonal 
  ridge 
  extends 
  to 
  the 
  lower 
  rostral 
  angle, 
  posterior 
  to 
  which 
  

   the 
  shell 
  is 
  smoother 
  than 
  elsewhere 
  and 
  marked 
  with 
  several 
  faint, 
  

   radial 
  riblers. 
  The 
  general 
  surface 
  is 
  covered 
  with 
  irregular, 
  uneven 
  

   and 
  often 
  rather 
  faint, 
  concentric 
  undulations, 
  separated 
  by 
  rather 
  wide 
  

   concave 
  intervals 
  which, 
  like 
  the 
  elevations, 
  are 
  covered 
  by 
  thin, 
  

   elevated 
  lines 
  of 
  growth. 
  The 
  undulations 
  are 
  most 
  regular 
  on 
  the 
  

   umbos 
  and 
  become 
  less 
  distinct 
  and 
  more 
  irregular 
  toward 
  the 
  margin 
  

   and 
  anteriorly, 
  and 
  show 
  by 
  transparency 
  on 
  the 
  interior 
  of 
  the 
  shell. 
  

   The 
  chondrophore 
  is 
  small, 
  but 
  very 
  prominent, 
  spoon-shaped, 
  narrow 
  

   at 
  the 
  base 
  and 
  expanded 
  distally, 
  with 
  a 
  nearly 
  round 
  resilial 
  pit. 
  

   The 
  ossicle 
  is 
  well 
  developed, 
  bent 
  into 
  a 
  crescent 
  shape, 
  and 
  so 
  formed 
  

   as 
  to 
  tit 
  into 
  the 
  small 
  rounded 
  notch 
  in 
  the 
  shell 
  margin 
  in 
  front 
  of 
  

   the 
  chondrophores. 
  A 
  somewhat 
  elevated 
  submarginal 
  ridge 
  extends 
  

   forward 
  from 
  the 
  notch 
  and 
  serves 
  to 
  support 
  the 
  thin 
  ligament: 
  a 
  

   similar 
  but 
  less 
  prominent 
  ridge 
  extends 
  backward 
  from 
  the 
  chondro- 
  

   phores 
  and 
  defines 
  a 
  distinct 
  ligamental 
  groove. 
  

  

  1 
  

  

  