﻿NO. 
  1139. 
  DEEP-WATEB 
  MOLLUSCA-VEBRILL 
  AND 
  BUSH. 
  825 
  

  

  LIMATULA 
  HYALINA, 
  new 
  species. 
  

  

  Shell 
  small, 
  tliiu, 
  traasluceut, 
  vertically 
  ovate, 
  somewhat 
  oblique, 
  

   aud 
  produced 
  postero-veutrally. 
  Hinge- 
  line 
  straight, 
  rather 
  short, 
  

   forming 
  a 
  well-marked 
  angle 
  at 
  each 
  end 
  owing 
  to 
  the 
  outline 
  of 
  each 
  

   margin 
  becoming 
  somewhat 
  concave 
  below. 
  Beaks 
  small, 
  acute, 
  in- 
  

   curved. 
  Umbos 
  prominent, 
  smooth, 
  beyond 
  which 
  the 
  shell 
  is 
  covered 
  

   with 
  numerous, 
  clearly 
  defined, 
  rather 
  sharp 
  radial 
  ridges, 
  separated 
  

   by 
  wider 
  concave 
  intervals 
  ; 
  from 
  twenty 
  to 
  twenty-five 
  of 
  the 
  radii 
  can 
  

   be 
  easily 
  counted; 
  toward 
  the 
  posterior 
  margin 
  they 
  become 
  faint 
  and 
  

   indistinct, 
  while 
  the 
  extreme 
  margin, 
  on 
  both 
  sides, 
  is 
  smooth. 
  The 
  

   anterior 
  margin 
  is 
  broadly 
  rounded 
  and 
  slopes 
  backward 
  below 
  the 
  

   middle; 
  the 
  posterior 
  margin 
  is 
  nearly 
  straight 
  or 
  even 
  a 
  little 
  incurved 
  

   in 
  its 
  upper 
  half, 
  but 
  becomes 
  slightly 
  convex 
  below; 
  the 
  ventral 
  mar- 
  

   gin 
  is 
  evenly 
  rounded 
  and 
  the 
  edge 
  is 
  slightly 
  scalloped 
  by 
  the 
  radial 
  

   ribs 
  and 
  furrows. 
  There 
  is 
  no 
  distinct 
  median 
  sulcus 
  or 
  larger 
  ribs. 
  

   The 
  ligamental 
  area 
  is 
  rather 
  short 
  and 
  broad 
  with 
  a 
  relatively 
  large 
  

   and 
  thick 
  central 
  ligament 
  which 
  occupies 
  a 
  distinctly 
  excavated 
  pit 
  in 
  

   the 
  hinge-margin. 
  

  

  Leno'th 
  of 
  one 
  of 
  the 
  largest 
  specimens, 
  4.5 
  mm. 
  ; 
  height, 
  7.5 
  mm. 
  ; 
  

   thickness, 
  3 
  mm. 
  

  

  A 
  number 
  of 
  live 
  sj)ecimens, 
  among 
  Foraminifera, 
  stations 
  2307 
  to 
  

   2374, 
  N. 
  lat. 
  29° 
  +, 
  W. 
  long. 
  85^ 
  +, 
  in 
  25 
  to 
  27 
  fathoms, 
  1885. 
  

  

  This 
  species 
  somewhat 
  resembles 
  Limatula 
  confuna 
  Smith, 
  which 
  was 
  

   also 
  taken 
  in 
  the 
  north 
  Atlantic 
  and 
  West 
  Indian 
  areas, 
  in 
  450 
  to 
  1,450 
  

   fathoms. 
  Our 
  species 
  is, 
  however, 
  more 
  compressed 
  and 
  more 
  oblique, 
  

   and 
  the 
  radial 
  ribs 
  do 
  not 
  extend 
  to 
  the 
  extreme 
  margins 
  as 
  in 
  the 
  lat- 
  

   ter. 
  The 
  hinge-margin 
  is 
  also 
  relatively 
  shorter 
  and 
  the 
  ligamental 
  

   area 
  larger, 
  so 
  that 
  the 
  beaks 
  are 
  more 
  separated. 
  

  

  Family 
  PECTINID.E. 
  

  

  In 
  this 
  family 
  the 
  classification 
  adopted 
  is 
  that 
  proposed 
  by 
  the 
  

   senior 
  author 
  in 
  a 
  recent 
  paper 
  on 
  the 
  group.' 
  We 
  give 
  here 
  a 
  brief 
  

   abstract 
  of 
  the 
  existing 
  genera 
  and 
  subgenera 
  therein 
  described. 
  For 
  

   fuller 
  discussions 
  of 
  the 
  characters 
  and 
  interrelations 
  of 
  these 
  groui)S 
  

   and 
  illustrations 
  of 
  typical 
  species 
  of 
  most 
  of 
  them, 
  reference 
  should 
  

   be 
  had 
  to 
  that 
  article. 
  

  

  In 
  the 
  following 
  synopsis 
  the 
  generic 
  groups 
  are 
  arranged 
  in 
  chrono- 
  

   logical 
  order, 
  without 
  regard 
  to 
  their 
  zoological 
  affinities. 
  

  

  ' 
  "A 
  study 
  of 
  the 
  family 
  P«'ctinida>, 
  with 
  a 
  revision 
  of 
  the 
  Genera 
  and 
  Subgenera." 
  

   By 
  A. 
  E. 
  Verrill, 
  Traus. 
  Coun. 
  Acad, 
  of 
  Sciences, 
  X, 
  j)p. 
  43-95 
  (six 
  jjlates), 
  July, 
  1897. 
  

  

  