﻿A 
  STUDY 
  IN 
  OARCINOLOGY. 
  73 
  

  

  of 
  burrowing 
  in 
  the 
  sand 
  for 
  protection 
  and 
  concealment. 
  A 
  decapod 
  

   crustacean 
  which 
  habitually 
  passes 
  a 
  large 
  part 
  of 
  its 
  existence 
  buried 
  in 
  the 
  

   sand, 
  must 
  undergo 
  a 
  considerable 
  modification 
  of 
  its 
  respiratory 
  arrange- 
  

   ments, 
  and 
  I 
  have 
  attempted 
  to 
  give 
  an 
  intelligible 
  account 
  of 
  these 
  modifi- 
  

   cations 
  in 
  the 
  various 
  members 
  of 
  the 
  Grymnopleura. 
  In 
  the 
  end 
  they 
  lead, 
  

   as 
  is 
  natural 
  enough, 
  to 
  the 
  suppression 
  of 
  the 
  inhalant 
  current 
  at 
  the 
  hind 
  

   end 
  of 
  the 
  thorax 
  and 
  to 
  the 
  substitution 
  of 
  inhalant 
  currents 
  in 
  the 
  antennary 
  

   region. 
  I 
  have 
  said, 
  in 
  the 
  earlier 
  part 
  of 
  this 
  memoir, 
  that 
  the 
  Gymnopleura 
  

   are 
  crabs 
  Inj 
  definition. 
  They 
  retain 
  so 
  many 
  Macruran 
  features 
  that 
  they 
  

   cannot 
  be 
  said 
  to 
  be 
  crabs 
  by 
  ancestry, 
  and 
  there 
  is 
  one 
  small 
  Macruran 
  

   feature 
  which 
  I 
  have 
  omitted 
  to 
  mention 
  before 
  because 
  I 
  only 
  recognised 
  it 
  

   when 
  the 
  greater 
  part 
  of 
  this 
  paper 
  was 
  written. 
  The 
  statocyst, 
  usually 
  

   closed 
  in 
  the 
  Brachyura, 
  is 
  open 
  in 
  the 
  Gymnopleura. 
  Certainly 
  so 
  in 
  Ranina, 
  

   Notosceles, 
  and 
  Lyreidus, 
  but 
  1 
  have 
  not 
  been 
  able 
  to 
  satisfy 
  myself 
  of 
  the 
  

   existence 
  of 
  the 
  aperture 
  in 
  all 
  the 
  species 
  examined 
  because 
  the 
  antennules 
  

   are 
  very 
  small 
  and 
  I 
  have 
  not 
  been 
  able 
  to 
  cut 
  sections. 
  The 
  position 
  of 
  the 
  

   aperture 
  of 
  the 
  statocyst 
  is 
  clearly 
  shown 
  in 
  fig. 
  34 
  for 
  Ranina. 
  

  

  I 
  must 
  conclude 
  with 
  a 
  description 
  and 
  definition 
  of 
  the 
  new 
  genus 
  and 
  

   species 
  JSotosceles 
  Chimmouis. 
  

  

  There 
  can 
  be 
  little 
  doubt 
  that 
  Raninoides 
  serratifrons 
  of 
  Henderson 
  (36) 
  

   belongs 
  to 
  the 
  genus 
  Notosceles 
  and 
  not 
  to 
  Raninoides, 
  but 
  his 
  species, 
  

   from 
  Ceylon, 
  is 
  different 
  to 
  mine. 
  He 
  mentions 
  another 
  example 
  of 
  

   serratifrons 
  from 
  Holothuria 
  Bank, 
  N.W. 
  Australia, 
  as 
  being 
  in 
  the 
  collec- 
  

   tions 
  of 
  the 
  British 
  Museum 
  of 
  Natural 
  History, 
  but 
  I 
  was 
  unable 
  to 
  find 
  

   it 
  there. 
  There 
  are 
  considerable 
  differences 
  between 
  Xotosceles 
  and 
  

   Raninoides, 
  many 
  of 
  which 
  have 
  been 
  referred 
  to 
  in 
  the 
  course 
  of 
  this 
  

   paper. 
  

  

  Notosceles, 
  nov. 
  gen. 
  

  

  Carapace 
  ovate, 
  convex 
  from 
  side 
  to 
  side, 
  minutely 
  punctate 
  or 
  smooth 
  

   for 
  the 
  most 
  part 
  but 
  granular 
  towards 
  the 
  frontal 
  region; 
  fronto-orbital 
  

   border 
  little 
  more 
  than 
  half 
  as 
  wide 
  as 
  the 
  broadest 
  part 
  of 
  the 
  carapace; 
  the 
  

   frontal 
  region 
  marked 
  off 
  by 
  a 
  slight 
  transverse 
  ridge 
  joining 
  the 
  bases 
  of 
  

   the 
  extra-orbital 
  spines 
  ; 
  the 
  rostrum 
  pointed, 
  fairly 
  prominent 
  with 
  two 
  

   flat 
  lateral 
  and 
  basal 
  teeth. 
  Ocular 
  peduncles 
  rather 
  short, 
  their 
  terminal 
  

   joints 
  inflated, 
  their 
  corneas 
  of 
  moderate 
  size. 
  Antennal 
  peduncle 
  short 
  and 
  

   broad, 
  the 
  flagellum 
  small. 
  Merus 
  of 
  the 
  third 
  maxilliped 
  little 
  more 
  than 
  

   hulf 
  as 
  long 
  as 
  the 
  ischium. 
  The 
  second 
  and 
  third 
  sternal 
  elements 
  of 
  the 
  

   sternal 
  shield 
  (sterna 
  xi 
  & 
  xii) 
  broad 
  and 
  convex 
  in 
  front, 
  but 
  narrowed 
  

   posteriorly 
  so 
  that 
  the 
  bases 
  of 
  the 
  first 
  as 
  well 
  as 
  the 
  second 
  pereiopods 
  are 
  

   approximated 
  to 
  the 
  middle 
  line. 
  Last 
  pair 
  of 
  pereiopods 
  reduced 
  in 
  size, 
  

   situated 
  above 
  and 
  in 
  front 
  of 
  the 
  penultimate 
  pair, 
  their 
  dactyli 
  small, 
  oval, 
  

  

  