﻿2 
  W. 
  H. 
  FLOWEK 
  ON 
  A 
  HALTTHEKITJM 
  

  

  posterior 
  part 
  at 
  the 
  fronto-parietal 
  suture, 
  and 
  in 
  a 
  line 
  descending 
  

   vertically 
  therefrom. 
  This 
  portion 
  has 
  then 
  heen 
  subjected 
  to 
  severe 
  

   attrition, 
  by 
  which 
  the 
  greater 
  part 
  of 
  the 
  premaxillary 
  rostrum, 
  the 
  

   orbital 
  processes 
  of 
  the 
  frontals, 
  and 
  the 
  zygomatic 
  processes 
  of 
  the 
  

   maxillaries, 
  and 
  other 
  projecting 
  parts, 
  have 
  been 
  removed.- 
  In 
  

   consequence 
  of 
  this, 
  what 
  may 
  be 
  called 
  the 
  external 
  features 
  of 
  the 
  

   skull, 
  which 
  are 
  especially 
  necessary 
  to 
  determine 
  its 
  closer 
  affinities, 
  

   are 
  greatly 
  marred, 
  though 
  enough 
  remains 
  of 
  its 
  essential 
  structure 
  to 
  

   enable 
  us 
  to 
  pronounce 
  with 
  confidence 
  as 
  to 
  its 
  general 
  relationship 
  

   to 
  known 
  forms. 
  Fortunately 
  the 
  whole 
  of 
  the 
  portion 
  of 
  the 
  maxillae 
  

   in 
  which 
  the 
  molar 
  series 
  of 
  teeth 
  are 
  implanted 
  is 
  preserved 
  ; 
  and 
  

   though 
  the 
  teeth 
  have 
  fallen 
  from 
  the 
  alveoli 
  in 
  the 
  front 
  part 
  of 
  the 
  

   series, 
  and 
  in 
  the 
  posterior 
  part 
  are 
  ground 
  down 
  to 
  mere 
  stumps, 
  so 
  

   that 
  the 
  form 
  of 
  the 
  crowns 
  cannot 
  be 
  ascertained 
  in 
  any 
  way, 
  many 
  

   important 
  dental 
  characters 
  may 
  still 
  be 
  deduced 
  from 
  the 
  number, 
  

   form, 
  size, 
  and 
  position 
  of 
  the 
  sockets 
  and 
  roots 
  that 
  remain. 
  

  

  As 
  the 
  intensely 
  hard 
  ivory-like 
  rostra 
  of 
  the 
  ziphioid 
  cetaceans, 
  

   the 
  tympanic 
  bones 
  of 
  the 
  Bakenidae, 
  and 
  the 
  teeth 
  of 
  terrestrial 
  

   mammals 
  almost 
  alone 
  remain 
  in 
  these 
  deposits 
  to 
  attest 
  the 
  former 
  

   existence 
  of 
  their 
  owners, 
  it 
  is 
  doubtless 
  to 
  the 
  extreme 
  massiveness 
  

   and 
  density 
  of 
  the 
  cranial 
  bones, 
  so 
  characteristic 
  of 
  the 
  order 
  Sirenia, 
  

   that 
  we 
  owe 
  the 
  preservation 
  of 
  so 
  large 
  a 
  portion 
  of 
  the 
  skull, 
  under 
  

   the 
  very 
  unfavourable 
  conditions 
  to 
  which, 
  in 
  common 
  with 
  the 
  

   other 
  fossils 
  of 
  this 
  formation, 
  it 
  must 
  have 
  been 
  exposed. 
  

  

  A 
  comparison 
  of 
  the 
  fragment 
  with 
  the 
  skulls 
  of 
  the 
  two 
  existing 
  

   forms 
  of 
  Sirenia, 
  the 
  Manati 
  (Manatus) 
  and 
  the 
  Dugong 
  {Halicore), 
  

   gives 
  the 
  following 
  results. 
  

  

  As 
  regards 
  size, 
  the 
  skull 
  must 
  have 
  been 
  considerably 
  larger 
  than 
  

   that 
  of 
  either 
  of 
  those 
  animals, 
  as 
  the 
  following 
  comparison 
  of 
  some 
  

   of 
  its 
  dimensions 
  with 
  those 
  of 
  a 
  full-sized 
  American 
  Manati 
  and 
  

   an 
  Australian 
  Dugong 
  will 
  show 
  : 
  — 
  

  

  

  Halitherium. 
  

  

  Manatus. 
  

  

  Halicore. 
  

  

  Length 
  of 
  upper 
  surface 
  from 
  "| 
  

   fronto-parietal 
  suture 
  to 
  pos- 
  1 
  

   terior 
  edge 
  of 
  anterior 
  narial 
  | 
  

  

  Height 
  of 
  skull 
  from 
  upper 
  "| 
  

   surface 
  of 
  frontal 
  bones 
  to 
  j- 
  

   lower 
  surface 
  of 
  palate-bones 
  J 
  

  

  Width 
  of 
  skull 
  in 
  temporal 
  1 
  

  

  Width 
  inside 
  anteorbital 
  fora- 
  "1 
  

  

  Width 
  between 
  widest 
  part 
  of 
  1 
  

   outer 
  border 
  of 
  maxillary 
  I 
  

  

  metre. 
  

   0-115* 
  

  

  0-153 
  

  

  0-070 
  

   0-095 
  

  

  0-114 
  

  

  metre. 
  

   0-095 
  

  

  0120 
  

  

  0050 
  

   0-062 
  

  

  0-064 
  

  

  metre. 
  

   0-065 
  

  

  0115 
  

  

  0-070 
  

   0-058 
  

  

  0-067 
  

  

  The 
  posterior 
  surface 
  of 
  the 
  fragment 
  (fig. 
  1) 
  shows 
  in 
  its 
  iipper 
  

   part 
  the 
  concave 
  impression 
  of 
  the 
  anterior 
  cerebral 
  lobes, 
  with 
  a 
  

  

  * 
  Something 
  should 
  be 
  allowed 
  for 
  wearing 
  of 
  the 
  edges 
  of 
  the 
  bone 
  to 
  make 
  

   the 
  comparison 
  exact. 
  

  

  