﻿874 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM. 
  vol.xx. 
  

  

  The 
  subgenus 
  Pseudomalletia, 
  proposed 
  by 
  Fischer 
  for 
  M. 
  ohtusa, 
  was 
  

   based 
  on 
  an 
  erroneous 
  description 
  of 
  the 
  siphon 
  tubes. 
  

  

  The 
  following 
  are 
  some 
  of 
  the 
  known 
  species: 
  

  

  M. 
  chilensis 
  Desnioulins, 
  Valparaiso 
  (Type); 
  M. 
  ohtusa 
  (Sars) 
  Morch, 
  

   from 
  off 
  Cape 
  Fear, 
  North 
  Carolina, 
  northward; 
  M. 
  polita 
  Verrill 
  and 
  

   Bush, 
  oft' 
  Delaware 
  Bay; 
  M. 
  abyssornm 
  Verrill 
  and 
  Bush, 
  off" 
  Chesa- 
  

   peake 
  Bay; 
  M. 
  cuneata 
  Jeffreys, 
  North 
  Atlantic; 
  M. 
  imllida 
  Smith, 
  

   Mid-South 
  Atlantic; 
  M. 
  arrouana 
  Smith 
  and 
  M, 
  dunleri 
  Smith, 
  

   Pacific; 
  and 
  M. 
  bellardii 
  Seguenza, 
  fossil. 
  

  

  MALLETIA 
  OBTUSA 
  (M. 
  Sars) 
  Morch. 
  

   (PlatcXCVII, 
  fig.4.) 
  

  

  Toldia 
  ohtusa 
  G. 
  O. 
  Sars, 
  Remarkable 
  Forms 
  of 
  Animal 
  Life, 
  p. 
  23, 
  pi. 
  ill, 
  figs. 
  

   16-20, 
  1872. 
  

  

  Mallctia 
  ohtusa 
  G. 
  0. 
  Sars, 
  Mollusca 
  Reg. 
  Arcticip 
  NorvegiiP, 
  p. 
  41, 
  pi. 
  19, 
  figs. 
  

   3, 
  a-h, 
  1878. 
  — 
  Jeffreys, 
  Proc. 
  Zool. 
  Soc, 
  London, 
  p. 
  586, 
  June, 
  1879. 
  — 
  Ver- 
  

   rill, 
  Tran.s. 
  Conn. 
  Acad., 
  VI, 
  pp. 
  226, 
  280, 
  1884; 
  Expl. 
  Alhafross, 
  Report 
  U. 
  S. 
  

   Com. 
  Fish 
  and 
  Fisheries 
  for 
  1883, 
  p. 
  576, 
  1885. 
  — 
  Smith, 
  E. 
  A., 
  Report 
  Voy. 
  

   Challenger, 
  Zool. 
  Lamellihranchiata, 
  XIII, 
  p. 
  245, 
  1885.— 
  Dall, 
  Bull. 
  IJ. 
  S. 
  

   Nat. 
  Mus., 
  No. 
  37, 
  p. 
  46, 
  1889.— 
  Bus?i, 
  Bui. 
  Mus. 
  Comp. 
  Zool., 
  XXIII, 
  p. 
  234, 
  

   1893. 
  — 
  LoCARD, 
  Campague 
  du 
  Caitdan, 
  Anuales 
  de 
  I'Universitd 
  de 
  Lyon, 
  

   p. 
  202, 
  1896.— 
  Verrill 
  and 
  Bush, 
  Amer. 
  Journ. 
  Sci., 
  Ill, 
  p. 
  57, 
  fig. 
  9, 
  1897. 
  

  

  The 
  soft 
  parts 
  of 
  several 
  specimens, 
  rather 
  poorly 
  preserved 
  in 
  alco- 
  

   hol, 
  have 
  been 
  examined. 
  They 
  have 
  a 
  large 
  foot 
  with 
  an 
  ovate 
  disk 
  

   pointed 
  in 
  front 
  and 
  minutely 
  crenulated. 
  The 
  siphon 
  tube 
  is 
  rather 
  

   long 
  and 
  slender, 
  in 
  some 
  cases 
  not 
  entirely 
  retracted 
  within 
  the 
  shell; 
  

   it 
  appears 
  to 
  contain 
  both 
  the 
  branchial 
  and 
  anal 
  tubes 
  which 
  are 
  

   closely 
  united 
  quite 
  to 
  the 
  simple 
  tips; 
  at 
  the 
  inner 
  base, 
  there 
  is 
  a 
  

   well-marked 
  siphonal 
  septum. 
  The 
  gills 
  are 
  small, 
  elongated, 
  pointed 
  

   posteriorly, 
  and 
  have 
  the 
  structure 
  usual 
  in 
  the 
  family. 
  The 
  palpi 
  are 
  

   rather 
  large, 
  elougated, 
  with 
  revolute 
  margins; 
  the 
  palpal 
  tentacle 
  is 
  

   very 
  long 
  and 
  slender, 
  and 
  in 
  the 
  contracted 
  state 
  variously 
  bent 
  with 
  

   the 
  edge 
  much 
  convoluted. 
  No 
  pallial 
  tentacle 
  was 
  found 
  at 
  the 
  base 
  

   of 
  the 
  siphon. 
  

  

  In 
  our 
  collection 
  there 
  is 
  a 
  large 
  series 
  of 
  this 
  species; 
  the 
  form 
  is 
  

   pretty 
  constant 
  and 
  in 
  nearly 
  all 
  cases 
  is 
  more 
  oblong 
  than 
  the 
  Euro- 
  

   l^an 
  species, 
  as 
  figured 
  by 
  G. 
  O. 
  Sars. 
  The 
  small 
  specimens 
  are 
  com- 
  

   pressed 
  while 
  the 
  large 
  ones 
  arfe 
  a 
  little 
  swollen. 
  The 
  umbos 
  are 
  

   small, 
  but 
  slightly 
  elevated; 
  the 
  beaks 
  are 
  very 
  small, 
  turned 
  directly 
  

   inward, 
  and 
  are 
  almost 
  in 
  contact 
  with 
  the 
  margin, 
  so 
  that 
  they 
  are 
  

   generally 
  worn 
  away 
  in 
  the 
  larger 
  specimens. 
  Directly 
  under, 
  and 
  

   partly 
  in 
  the 
  beaks, 
  and 
  also 
  cutting 
  more 
  or 
  less 
  into 
  the 
  thickness 
  of 
  

   the 
  external 
  side 
  of 
  the 
  hinge-margin, 
  there 
  is 
  a 
  small 
  notch, 
  or 
  shallow 
  

   excavation, 
  which 
  is 
  occupied 
  by 
  a 
  special 
  portion 
  of 
  the 
  ligament 
  

   that 
  probably 
  represents 
  a 
  remnant 
  of 
  a 
  degenerated 
  rcsiliiini. 
  The 
  

   true 
  ligament 
  is 
  well 
  developed 
  and 
  prominent 
  for 
  about 
  one-half 
  the 
  

   length 
  of 
  the 
  hinge-margin, 
  then 
  becomes 
  abruptly 
  thinner 
  and 
  nar- 
  

  

  