﻿830 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MVSEUM. 
  vcilxx. 
  

  

  ^QUIPECTEN 
  Fischer, 
  1887. 
  

  

  ^Equlpeclcn 
  (siiltgemis 
  of 
  C/Jawu/s) 
  Vkkkill, 
  Trans. 
  Conn. 
  Acad., 
  X. 
  pp. 
  5!), 
  (J7, 
  8!l, 
  

   91. 
  pi. 
  XVI, 
  figs. 
  6-11 
  ; 
  pi. 
  XX, 
  figs. 
  1-3, 
  6, 
  6rt, 
  18'J7. 
  

  

  Type. 
  — 
  JEquipecten 
  operctdaris 
  (Linnjieus). 
  

  

  Shell 
  broadly 
  rounded, 
  with 
  the 
  valves 
  uearly 
  equal 
  and 
  symmetrical. 
  

   Auricles 
  well-fonned, 
  aiigulai" 
  ; 
  byssal 
  notch 
  well-developed. 
  The 
  scul[»- 
  

   ture 
  consists 
  of 
  a 
  moderate 
  number 
  of 
  large 
  and 
  nearly 
  equal 
  primary 
  

   radial 
  ribs, 
  which 
  increase 
  in 
  size, 
  but 
  are 
  not 
  much 
  increased 
  in 
  num- 
  

   ber 
  with 
  age, 
  by 
  the 
  interpolation 
  of 
  new 
  ones. 
  Internal 
  ribs 
  or 
  

   flutings 
  correspond 
  to 
  external 
  grooves, 
  but 
  each 
  one 
  is 
  bicarinate 
  or 
  

   double, 
  esi>ecially 
  near 
  the 
  margins. 
  Hinge-plate 
  Avith 
  one 
  or 
  two 
  

   slightly 
  divergent 
  ribs 
  at 
  each 
  end, 
  often 
  crossed 
  by 
  strong 
  transverse 
  

   incisions. 
  Pectinidial 
  teeth 
  abortive 
  in 
  the 
  tyi)e, 
  but 
  present 
  in 
  most 
  

   species. 
  The 
  foot 
  of 
  the 
  type 
  species 
  is 
  subcylindrical, 
  well-developed, 
  

   with 
  a 
  byssal 
  fissure 
  and 
  a 
  terminal, 
  deeply 
  bilobed 
  -'■ 
  scooped-shaped 
  " 
  

   disk, 
  which 
  can 
  be 
  expanded. 
  In 
  JE. 
  irradians 
  ' 
  the 
  foot 
  has 
  a 
  similar 
  

   structure, 
  but 
  the 
  terminal 
  disk 
  ap[)ears 
  to 
  be 
  smaller. 
  

  

  PECTINELLA 
  Verrill, 
  1897. 
  

   rcrlini'Un 
  Vkkuili.. 
  Trans. 
  ("<nin. 
  Acad.. 
  X. 
  pp. 
  fiS, 
  90, 
  92, 
  1897. 
  

  

  Type. 
  — 
  ]*ectinella 
  sujabci 
  (J)all). 
  

  

  Shell 
  small, 
  thin, 
  swollen, 
  nearly 
  smootli, 
  with 
  convex 
  and 
  slightly 
  

   uncipial 
  valves. 
  Auricles 
  very 
  unetuial, 
  oblique, 
  the 
  anterior 
  larger, 
  

   with 
  a 
  deep 
  byssal 
  notch 
  in 
  the 
  right 
  valve, 
  but 
  without 
  pectinidial 
  

   teeth; 
  posterior 
  auricle 
  small. 
  The 
  surface 
  is 
  smooth 
  except 
  for 
  fine 
  

   lines 
  of 
  growth. 
  Camptonectes 
  sculpture 
  is 
  not 
  present. 
  The 
  texture 
  

   is 
  not 
  hyaline. 
  

  

  The 
  only 
  known 
  species 
  is 
  Fectmclla 
  su/sbei 
  (Dall)- 
  which 
  M^as 
  taken 
  

   by 
  the 
  Blake 
  Expedition 
  in 
  the 
  West 
  Indies, 
  in 
  158 
  iUthoms. 
  

  

  LISSOPECTEN 
  Verrill, 
  1897. 
  

  

  lAssopveten 
  (snbgeniis 
  of 
  Chlamys) 
  A'ekkill, 
  Traus. 
  Coun. 
  Acad., 
  X, 
  pp. 
  68, 
  90, 
  91, 
  

   1897. 
  

  

  Tyye. 
  — 
  Lissopecten 
  hyaUnus 
  (Poli). 
  

  

  Shell 
  slightly 
  ineqnivalve, 
  broadly 
  rounded, 
  not 
  ob]i([ue, 
  thin, 
  trans 
  

   lucent, 
  nearly 
  smooth. 
  The 
  external 
  sculpture 
  consists 
  of 
  faint, 
  uearly 
  

   obsolete 
  radial 
  ridges 
  and 
  obscure 
  riblets, 
  but 
  one 
  or 
  both 
  auricles 
  uniy 
  

   have 
  a 
  more 
  or 
  less 
  cancellated 
  sculpture. 
  The 
  interior 
  sculpture 
  con- 
  

   sists 
  of 
  very 
  distinct, 
  simple, 
  raised 
  ribs. 
  Auricles 
  angular, 
  well-devel- 
  

   oi)ed, 
  Byssal 
  notch 
  deep. 
  Pectinidial 
  teeth 
  prominent. 
  Margin 
  not 
  

   scalloped, 
  nearly 
  plain 
  and 
  simple. 
  

  

  ' 
  Trans. 
  Conn. 
  Acad., 
  X, 
  pi. 
  xx, 
  fig. 
  6. 
  

  

  * 
  Bull. 
  Mu8. 
  Comp. 
  Zo.il., 
  XII, 
  p. 
  223, 
  pi. 
  iv, 
  fig. 
  2, 
  1886. 
  

  

  