﻿864 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  2irSEUM. 
  

  

  Found 
  ill 
  considerable 
  numbers, 
  at 
  about 
  forty 
  -five 
  stations, 
  between 
  

   K 
  lat. 
  47° 
  40', 
  W. 
  long. 
  47° 
  lio' 
  30", 
  and 
  N. 
  lat. 
  35° 
  12' 
  10", 
  W. 
  long-. 
  74° 
  

   .57' 
  15", 
  in 
  20i 
  to 
  781 
  fathoms, 
  1872-1880. 
  

  

  This 
  species 
  is 
  more 
  elongated 
  and 
  more 
  regularly 
  elliptical 
  than 
  any 
  

   of 
  the 
  allied 
  species; 
  the 
  hinge-margin 
  is 
  also 
  less 
  angulated. 
  

  

  A 
  single 
  specimen 
  (No. 
  74325), 
  station 
  43, 
  oft' 
  Cape 
  Sable,.in90 
  fathoms, 
  

   1877, 
  at 
  first 
  thought 
  to 
  be 
  a 
  distinct 
  species, 
  differs 
  from 
  the 
  typical 
  

   form 
  in 
  being 
  more 
  oblong 
  with 
  the 
  ventral 
  margin 
  less 
  curved, 
  the 
  

   posterior 
  end 
  more 
  evenly 
  rounded 
  with 
  only 
  a 
  slight 
  indication 
  of 
  a 
  

   superior 
  angulation, 
  so 
  that 
  the 
  shell 
  has 
  a 
  pretty 
  regular, 
  narrow 
  ellip- 
  

   tical 
  form. 
  In 
  all 
  other 
  respects, 
  however, 
  it 
  agrees 
  well 
  with 
  the 
  ordi- 
  

   nary 
  form. 
  This 
  sjoecimen, 
  which 
  receives 
  the 
  varietal 
  name 
  strieta, 
  

   is 
  figured 
  on 
  Plate 
  LXXX, 
  fig. 
  1. 
  

  

  Length, 
  5 
  mm.; 
  height, 
  3 
  mm.; 
  breadth, 
  1.3 
  mm.; 
  length 
  from 
  beak 
  

   to 
  posterior 
  end, 
  3 
  mm. 
  

  

  YOLDIELLA 
  INFLATA 
  Verrill 
  and 
  Bush. 
  

  

  (Plates 
  LXXX, 
  fig. 
  8; 
  LXXXII, 
  figs. 
  5, 
  6.) 
  

  

  Yoldia 
  Incida 
  Verrill, 
  Trans. 
  Conn. 
  Acad., 
  VI, 
  p. 
  279, 
  1884 
  (in 
  part). 
  

   Yoldiella 
  inflata 
  Verrill 
  and 
  Brsii, 
  Amor. 
  Journ. 
  8ci., 
  Ill, 
  p. 
  .56, 
  figs. 
  .3, 
  4, 
  11, 
  

   January, 
  1897. 
  

  

  Shell 
  small, 
  swollen, 
  rather 
  short, 
  subovate, 
  with 
  the 
  posterior 
  end 
  

   broad, 
  angulated 
  postero-dorsally; 
  beaks 
  at 
  about 
  the 
  anterior 
  third; 
  

   surface 
  smooth. 
  An 
  tero 
  dorsal 
  margin 
  regularly 
  convex 
  and 
  sloping 
  

   rapidly 
  to 
  the 
  anterior 
  end 
  which 
  is 
  evenly 
  rounded, 
  very 
  obtuse, 
  and 
  

   passes 
  insensibly 
  into 
  the 
  evenly 
  curved 
  ventral 
  margin 
  which 
  is 
  

   decidedly 
  convex, 
  although 
  the 
  degree 
  of 
  convexity 
  varies 
  considerably 
  

   in 
  different 
  specimens; 
  the 
  posterior 
  end 
  is 
  obliquely 
  subtruncated, 
  

   with 
  an 
  obtuse 
  curve 
  below 
  and 
  an 
  obtusely 
  rounded 
  angle 
  at 
  its 
  uj^per 
  

   extremity 
  where 
  it 
  joins 
  the 
  nearly 
  straight 
  postero-dorsal 
  margin. 
  

   The 
  umbos 
  are 
  full 
  and 
  well-rounded 
  but 
  not 
  very 
  prominent; 
  the 
  

   beaks 
  are 
  small, 
  directly 
  incurved, 
  appressed 
  to 
  the 
  margin. 
  There 
  is 
  

   no 
  distinct 
  lunule 
  but 
  the 
  margin 
  is 
  slightly 
  pinched 
  up 
  in 
  a 
  small 
  crest 
  

   both 
  before 
  and 
  behind 
  the 
  beaks. 
  The 
  ligament 
  is 
  delicate 
  and 
  shows 
  

   slightly 
  on 
  both 
  sides 
  of 
  the 
  beak. 
  Epidermis 
  pale 
  olive 
  yellow 
  or 
  straw 
  

   color; 
  surface 
  smooth, 
  shining, 
  reflecting 
  prismatic 
  colors, 
  showing 
  

   more 
  or 
  less 
  distinct 
  lines 
  of 
  growth 
  which 
  sometimes 
  become 
  regular, 
  

   concentric, 
  very 
  fine 
  striations, 
  esjiecially 
  anteriorly. 
  Hinge-margin 
  

   well 
  developed, 
  moderately 
  broad 
  and 
  considerably 
  thickened, 
  forming 
  

   an 
  obtuse 
  angle 
  at 
  the 
  beak 
  where 
  it 
  is 
  thin, 
  encroached 
  upon 
  by 
  the 
  

   beak 
  and 
  interrupted 
  by 
  the 
  cartilage-pit; 
  the 
  two 
  portions 
  are 
  nearly 
  

   equal 
  in 
  length, 
  the 
  anterior 
  somewhat 
  arched, 
  the 
  jiosterior 
  nearly 
  

   straight, 
  each 
  having 
  a 
  thin, 
  smooth 
  border 
  above 
  the 
  teeth, 
  about 
  

   equal 
  in 
  breadth 
  to 
  the 
  hinge-plate. 
  In 
  the 
  largest 
  specimens 
  there 
  

   are 
  nine 
  to 
  eleven 
  (most 
  frequently 
  ten) 
  rather 
  stout, 
  angular 
  teeth 
  and 
  

   about 
  ten 
  very 
  similar 
  posterior 
  ones; 
  the 
  cartilage-pit 
  is 
  small 
  and 
  

  

  