﻿NO.U39. 
  DEEF-WATER 
  MOLLVSCA 
  — 
  rERRILL 
  AND 
  BUSH. 
  881 
  

  

  showing 
  only 
  very 
  minute 
  papilUe 
  posteriorly. 
  The 
  foot 
  is 
  large 
  and 
  

   strong, 
  Avith 
  a 
  broad, 
  strongly 
  crenulated 
  and 
  striated, 
  concave 
  disk, 
  

   jpointed 
  in 
  front. 
  The 
  gills 
  are 
  well 
  developed 
  and 
  somewhat 
  triquetral, 
  

   The 
  palpal 
  tentacles 
  are 
  rather 
  large, 
  long, 
  tapered, 
  triquetral, 
  strongly 
  

   grooved, 
  curved 
  in 
  sickle-shape. 
  The 
  palpi 
  are 
  rather 
  broad 
  and 
  short. 
  

  

  The 
  following 
  are 
  some 
  of 
  the 
  known 
  species: 
  

  

  T. 
  arata 
  Bellardi, 
  and 
  T. 
  solida 
  Seguenza, 
  fossil, 
  in 
  the 
  Italian 
  ter- 
  

   tiary 
  formation; 
  T. 
  cytherea 
  Dall 
  = 
  T. 
  veneriformis 
  (Smith), 
  T. 
  amahiUs 
  

   Ball, 
  T. 
  virens 
  Dall, 
  T. 
  acinula 
  Dall, 
  T. 
  cuneata 
  (Smith) 
  = 
  T. 
  smifhii 
  

   Dall, 
  T. 
  lata 
  Verrill 
  and 
  Bush, 
  all 
  Florida 
  and 
  West 
  Indian 
  species; 
  

   and 
  T. 
  callistiformis 
  Verrill 
  and 
  Bush, 
  oft' 
  Chesaj)eake 
  Bay. 
  

  

  TINDARIA 
  CALLISTIFORMIS 
  Verrill 
  and 
  Bush. 
  

  

  (Plates 
  LXXVIII, 
  tig. 
  1; 
  LXXX, 
  tigs, 
  6, 
  7.) 
  

  

  Tinduria 
  caUislifortnis 
  Verrill 
  aud 
  Bush, 
  Amer. 
  Journ. 
  Sii.,III. 
  p. 
  59, 
  tigs. 
  10, 
  

   20, 
  21, 
  January, 
  1897. 
  

  

  Shell 
  small, 
  stout, 
  thick, 
  regularly 
  ovate, 
  sculptured 
  with 
  very 
  regu- 
  

   ular, 
  line, 
  concentric 
  grooves, 
  and 
  having 
  a 
  broad, 
  thick 
  hinge-margin 
  

   with 
  a 
  continuous 
  line 
  of 
  teeth 
  and 
  no 
  chondrophore. 
  Umbos 
  swollen, 
  

   beaks 
  prominent, 
  strongly 
  curved 
  inward 
  and 
  somewhat 
  forward, 
  with 
  

   the 
  nuclear 
  shell 
  (prodissoconch) 
  smooth 
  and 
  glossy. 
  The 
  lunular 
  

   area 
  is 
  somewhat 
  excavated 
  but 
  has 
  no 
  definite 
  boundary. 
  Anterior 
  

   end 
  considerably 
  shorter 
  than 
  the 
  posterior, 
  both 
  equally 
  and 
  evenly 
  

   rounded. 
  Antero 
  dorsal 
  margin 
  convex, 
  sloping 
  rather 
  rapidly 
  and 
  

   forming 
  a 
  continuous 
  curve 
  with 
  the 
  anterior 
  margin 
  which 
  is 
  also 
  

   continuous 
  with 
  the 
  more 
  broadly 
  convex 
  ventral 
  margin 
  : 
  the 
  poste- 
  

   rior 
  end 
  is 
  evenly 
  rounded, 
  with 
  the 
  dorsal 
  margin 
  strongly 
  convex, 
  

   sloping 
  gradually, 
  without 
  any 
  definite 
  angulation. 
  The 
  surfoce 
  is 
  

   covered 
  with 
  very 
  regular, 
  fine, 
  close, 
  concentric, 
  rounded 
  ridges, 
  sepa- 
  

   rated 
  by 
  semicircular 
  furrows 
  about 
  twice 
  their 
  width, 
  except 
  on 
  the 
  

   umbos 
  where 
  the 
  two 
  are 
  about 
  equal. 
  The 
  inner 
  ventral 
  margin 
  is 
  

   plain, 
  sharp, 
  aud 
  slightly 
  beveled. 
  The 
  hinge-margin 
  is 
  wide 
  and 
  

   thick, 
  narrowest 
  just 
  behind 
  the 
  beaks, 
  gradually 
  widening 
  and 
  thick- 
  

   ening 
  toward 
  both 
  ends. 
  The 
  anterior 
  portion 
  is 
  much 
  the 
  shorter 
  and 
  

   somewhat 
  the 
  wider 
  and 
  slopes 
  more 
  rapidly; 
  along 
  the 
  narrow 
  mid- 
  

   dle 
  portion 
  the 
  teeth 
  are 
  quite 
  small, 
  but 
  regular, 
  transverse, 
  and 
  sep- 
  

   arated 
  by 
  narrow 
  intervals; 
  owing 
  to 
  the 
  absence 
  of 
  a 
  chondrophore, 
  

   there 
  is 
  no 
  definite 
  center, 
  but 
  in 
  front 
  of 
  the 
  tip 
  of 
  the 
  beaks 
  there 
  

   are 
  about 
  eight 
  teeth 
  which 
  increase 
  rapidly 
  in 
  size 
  and 
  prominence, 
  

   the 
  four 
  distal 
  ones 
  being 
  large, 
  elevated, 
  and 
  somewhat 
  V-shaped; 
  

   behind 
  the 
  beak 
  there 
  are 
  about 
  twenty-three 
  teeth, 
  of 
  which 
  nine 
  or 
  

   ten 
  proximal 
  ones 
  are 
  small; 
  they 
  then 
  commence 
  to 
  increase 
  in 
  size 
  

   and 
  length 
  so 
  that 
  eight 
  or 
  nine 
  are 
  larger 
  and 
  higher 
  than 
  the 
  rest; 
  

   these 
  are, 
  however, 
  smaller 
  and 
  more 
  acute 
  than 
  the 
  larger 
  ones 
  in 
  the 
  

   anterior 
  portion; 
  two 
  or 
  three 
  distal 
  ones 
  are 
  a 
  little 
  less 
  elevated 
  than 
  

   Proc. 
  N. 
  M. 
  vol. 
  XX 
  uG 
  

  

  