﻿NO. 
  1139. 
  DEEP-WATER 
  MOLLUSCA—VEBBILL 
  AND 
  BUSH. 
  859 
  

  

  become 
  large, 
  strong, 
  and 
  thick 
  distally, 
  with 
  broad 
  V-shaped 
  bases 
  

   separated 
  by 
  deep 
  j)its. 
  In 
  the 
  posterior 
  series, 
  which 
  is 
  a 
  little 
  the 
  

   longer, 
  there 
  are 
  eleven 
  teeth 
  corresponding 
  in 
  form 
  and 
  arrangement 
  

   with 
  those 
  of 
  the 
  anterior 
  series. 
  The 
  exterior 
  surface 
  is 
  regularly 
  

   sculptured 
  with 
  prominent, 
  sharp, 
  concentric, 
  raised 
  lines 
  separated 
  by 
  

   wider 
  intervals. 
  Interior 
  very 
  glossy. 
  Muscular 
  scars 
  and 
  pallial 
  

   line 
  not 
  visible. 
  Exterior 
  sculpture 
  clearly 
  seen 
  through 
  the 
  shell. 
  

  

  Length, 
  4.2 
  mm.; 
  height, 
  2.8mm. 
  

  

  One 
  valve, 
  among 
  Foraniinifera, 
  station 
  2150, 
  N. 
  lat. 
  13° 
  34' 
  45", 
  W. 
  

   long. 
  810 
  20' 
  10", 
  in 
  382 
  fathoms, 
  1884. 
  

  

  ORTHOTOLDIA 
  Verrill 
  and 
  Bush, 
  1897. 
  

   Orthoijoldia 
  Verrill 
  and 
  Bush, 
  Amer. 
  Jouru. 
  Sci., 
  Ill, 
  pjj. 
  55,62, 
  January, 
  1897. 
  

  

  Type. 
  — 
  Orthoyoldia 
  scapina 
  (Dall). 
  

  

  Shell 
  oblong, 
  gaping, 
  blunt 
  or 
  rounded 
  at 
  both 
  ends, 
  without 
  a 
  dis- 
  

   tinct 
  rostrum; 
  no 
  carina. 
  Pallial 
  sinus 
  large 
  and 
  broad. 
  Teeth 
  

   numerous 
  in 
  both 
  series. 
  0. 
  scapina 
  (Dall), 
  from 
  ofl" 
  Brazil 
  and 
  0. 
  

   solenoides 
  (Dall) 
  from 
  the 
  West 
  Indies. 
  

  

  MEGAYOLDIA 
  Verrill 
  and 
  Bush, 
  1897. 
  

  

  MegayoJdia 
  Verrill 
  and 
  Bush, 
  Amer. 
  Journ. 
  Sci., 
  Ill, 
  pp. 
  55, 
  62, 
  fig, 
  17, 
  January, 
  

  

  1897. 
  

  

  Type. 
  — 
  Megayoldia 
  thraciaformis 
  (Storer). 
  

  

  We 
  have 
  established 
  a 
  new 
  generic 
  group 
  for 
  this 
  large 
  and 
  well- 
  

   known 
  species, 
  which 
  has 
  sometimes 
  been 
  referred 
  to 
  Yoldia 
  and 
  some- 
  

   times 
  to 
  Portlandia. 
  No 
  closely 
  allied 
  species 
  is 
  known. 
  It 
  is 
  proba- 
  

   bly 
  the 
  largest 
  known 
  species 
  of 
  this 
  family 
  and 
  is 
  remarkable 
  for 
  its 
  

   broad, 
  short, 
  compressed 
  form, 
  with 
  a 
  very 
  short, 
  blunt, 
  indefinite, 
  jios- 
  

   tero-dorsal 
  rostrum, 
  and 
  with 
  a 
  low 
  radial 
  ridge, 
  ending 
  in 
  a 
  postero- 
  

   ventral 
  marginal 
  lobe. 
  The 
  chondrophore 
  is 
  remarkably 
  large 
  and 
  

   strong, 
  concave, 
  striated 
  within, 
  and 
  projects 
  much 
  within 
  the 
  margin 
  

   of 
  the 
  hinge-plate. 
  The 
  pallial 
  sinus 
  is 
  large 
  and 
  deep. 
  In 
  outline 
  it 
  

   somewhat 
  resembles 
  typical 
  Portlandia, 
  but 
  differs 
  in 
  being 
  broader, 
  

   flatter, 
  and 
  gaping 
  at 
  both 
  ends, 
  and 
  in 
  having 
  a 
  strongly 
  developed 
  

   external 
  ligament. 
  From 
  Yoldia 
  it 
  also 
  differs 
  in 
  the 
  last 
  character, 
  as 
  

   well 
  as 
  in 
  outline, 
  but 
  agrees 
  with 
  it 
  in 
  its 
  compressed 
  gaping 
  shell. 
  

  

  The 
  postero- 
  ventral 
  margin 
  of 
  the 
  mantle 
  forms 
  a 
  jiouch-like 
  protru- 
  

   sion, 
  corresponding 
  to 
  the 
  radial 
  ridge. 
  The 
  sii^hon 
  tubes 
  are 
  long 
  and 
  

   united; 
  the 
  posterior 
  pallial 
  tentacle 
  is 
  long 
  and 
  slender. 
  The 
  palpi 
  

   are 
  very 
  large. 
  The 
  palpal 
  tentacles 
  originate 
  from 
  the 
  body- 
  wall 
  at 
  

   the 
  base 
  of 
  the 
  outer 
  palpi; 
  they 
  are 
  long 
  and 
  thick, 
  with 
  a 
  large 
  

   furrow 
  on 
  one 
  side. 
  

  

  