﻿296 
  Dr. 
  H. 
  B. 
  Brady 
  on 
  a 
  new 
  Type 
  of 
  Astrorhizidie. 
  

  

  arenaceous 
  ; 
  built 
  up 
  of 
  light-coloured 
  siliceous 
  sand 
  and 
  

   sponge-spicules, 
  the 
  latter 
  often 
  in 
  large 
  proportion, 
  together 
  

   with 
  a 
  few 
  Foraminifera 
  and 
  other 
  minute 
  organisms. 
  

   Diameter 
  of 
  the 
  figured 
  specimen 
  about 
  6 
  millim. 
  ; 
  but 
  frag- 
  

   ments 
  of 
  much 
  larger 
  examples 
  have 
  been 
  met 
  with. 
  

  

  " 
  Dredged 
  12th 
  to 
  13th 
  April, 
  1888 
  ; 
  depth 
  250 
  fathoms 
  ; 
  

   North 
  Sentinel 
  Island, 
  Andamans, 
  bearing 
  N. 
  15° 
  W. 
  18 
  

   miles 
  ; 
  bottom 
  green 
  mud 
  and 
  sand. 
  Multitudes 
  of 
  speci- 
  

   mens 
  came 
  up 
  on 
  the 
  tangle-bar, 
  with 
  a 
  capital 
  haul 
  of 
  

   Umbrellula, 
  siliceous 
  sponges, 
  and 
  Crustacea 
  of 
  deep-water 
  

   types." 
  

  

  Masonella 
  patelliformis, 
  n. 
  sp. 
  (Fig. 
  2.) 
  

  

  Test 
  free, 
  thin 
  ; 
  patelloid 
  or 
  subconical 
  ; 
  central 
  chamber 
  

   about 
  one 
  fourth 
  the 
  entire 
  diameter 
  of 
  the 
  test, 
  but 
  irregular 
  

   in 
  form 
  and 
  outline; 
  radial 
  tubes 
  from 
  0"05 
  to 
  0*1 
  millim. 
  in 
  

   diameter. 
  Colour 
  dark 
  ; 
  texture 
  loosely 
  arenaceous, 
  exterior 
  

   rough 
  ; 
  the 
  central 
  chamber 
  and 
  tubuli 
  more 
  strongly 
  marked 
  

   externally 
  on 
  the 
  convex 
  than 
  on 
  the 
  concave 
  face. 
  Dia- 
  

   meter 
  of 
  the 
  figured 
  specimen 
  10 
  millim., 
  but 
  fragments 
  

   indicate 
  that 
  this 
  is 
  by 
  no 
  means 
  the 
  maximum 
  size. 
  

  

  " 
  Dredged 
  11th 
  April, 
  1888 
  ; 
  depth 
  265 
  fathoms 
  ; 
  about 
  

   7 
  miles 
  S.E. 
  by 
  E. 
  of 
  Ross 
  Island, 
  Andamans 
  ; 
  bottom 
  green 
  

   mud. 
  The 
  specimens 
  came 
  up 
  in 
  great 
  numbers 
  on 
  the 
  

   swabs 
  which 
  were 
  attached 
  to 
  the 
  trawl." 
  

  

  Masonella 
  patelliformis 
  has 
  a 
  larger, 
  coarser, 
  and 
  darker- 
  

   coloured 
  test 
  than 
  M. 
  planulata, 
  and 
  its 
  radial 
  tubes 
  are 
  much 
  

   thinner 
  ; 
  its 
  contour 
  also 
  is 
  subconical, 
  whilst 
  that 
  of 
  the 
  

   latter 
  species 
  is 
  complanate. 
  

  

  The 
  accompanying 
  drawings 
  (woodcuts, 
  figs. 
  1, 
  2), 
  made 
  

   by 
  a 
  native 
  artist, 
  give 
  a 
  tolerably 
  accurate 
  idea 
  of 
  the 
  two 
  

   organisms. 
  Fig. 
  1 
  a, 
  represents 
  the 
  lateral 
  aspect 
  of 
  M. 
  

   planulata, 
  1 
  b, 
  a 
  diagram 
  of 
  its 
  transverse 
  section 
  ; 
  fig. 
  2 
  a, 
  

   M. 
  patelliformis, 
  2 
  b, 
  diagram 
  of 
  transverse 
  section 
  ; 
  all 
  mag- 
  

   nified 
  5 
  diameters. 
  

  

  Calcutta, 
  

   4th 
  January, 
  1889. 
  

  

  