﻿112 
  THE 
  EXTINCT 
  BATRACHIA, 
  REPTILIA 
  

  

  In 
  Laelaps 
  it 
  is 
  shorter 
  than 
  in 
  any 
  known 
  Dinosaur, 
  measuring 
  less 
  than 
  the 
  hind 
  limb 
  

   by 
  a 
  foot. 
  It 
  was 
  cylindrical, 
  slender 
  towards 
  the 
  tip, 
  and 
  in 
  fact 
  not 
  unlike 
  that 
  of 
  a 
  dog, 
  

   and 
  probably 
  capable 
  of 
  motion 
  similar 
  to 
  the 
  latter. 
  When 
  the 
  Laelaps 
  stood 
  erect, 
  the 
  

   tail 
  would 
  trail 
  its 
  extremity 
  on 
  the 
  ground, 
  but 
  could 
  furnish 
  little 
  support. 
  

  

  Comparison 
  with 
  other 
  Dinosauria. 
  — 
  The 
  species 
  with 
  which 
  detailed 
  comparison 
  can 
  

   be 
  made, 
  are 
  the 
  Poecilopleurum 
  bucklandii 
  Deslongchamps, 
  and 
  Megalosaurus 
  bucklandii 
  

   Mantell. 
  All 
  three 
  were 
  of 
  nearly 
  similar 
  size. 
  The 
  Poecilopleurum 
  is 
  better 
  known 
  

   than 
  the 
  Megalosaurus, 
  and 
  furnishes 
  many 
  similar 
  parts. 
  Thus 
  the 
  humeri 
  possess 
  the 
  

   the 
  same 
  disproportionately 
  small 
  size, 
  the 
  extremity 
  of 
  the 
  tibia 
  is 
  similarly 
  expanded 
  and 
  

   flattened, 
  and 
  is 
  similarly 
  embraced 
  by 
  the 
  astragalus. 
  There 
  are, 
  however, 
  abundant 
  

   specific 
  differences 
  in 
  all 
  the 
  bones 
  described 
  by 
  Deslongchamps. 
  In 
  the 
  same 
  manner 
  

   the 
  Laelaps 
  aquilunguis 
  presents 
  abundant 
  specific 
  difference 
  from 
  the 
  Megalosaurus 
  buck- 
  

   landii. 
  The 
  slender, 
  curved 
  femur 
  differs 
  from 
  the 
  massive 
  straight 
  one 
  of 
  the 
  latter 
  ; 
  the 
  

   tibia 
  is 
  more 
  slender, 
  and 
  more 
  flattened 
  distally; 
  its 
  extremity 
  is 
  wedge-shaped, 
  not 
  

   rhombic 
  as 
  in 
  European 
  species. 
  The 
  claws 
  of 
  the 
  Megalosaurus 
  are 
  relatively 
  shorter 
  

   and 
  less 
  curved. 
  

  

  The 
  generic 
  relations 
  with 
  these 
  two 
  types 
  must 
  be 
  understood. 
  Laelaps 
  is 
  obviously 
  

   distinct 
  from 
  Paecilopleurum 
  in 
  the 
  structure 
  of 
  its 
  feet. 
  In 
  the 
  former 
  the 
  phalanges 
  are 
  

   slender, 
  in 
  the 
  latter 
  massive, 
  and 
  mostly 
  broad. 
  The 
  claws 
  are 
  more 
  different 
  ; 
  in 
  the 
  

   former 
  compressed 
  and 
  hooked 
  ; 
  as 
  broad 
  as 
  deep 
  in 
  the 
  latter, 
  and 
  but 
  little 
  curved. 
  

   They 
  are 
  prehensile 
  in 
  the 
  former, 
  in 
  the 
  latter 
  not 
  at 
  all, 
  or 
  adapted 
  only 
  for 
  defense 
  ; 
  

   they 
  present 
  a 
  very 
  small 
  point 
  of 
  insertion, 
  compared 
  with 
  the 
  large 
  knob 
  of 
  the 
  former 
  ; 
  

   they 
  also 
  exhibit 
  a 
  deep 
  groove 
  on 
  the 
  side, 
  which 
  is 
  weak 
  in 
  Laelaps. 
  The 
  difference 
  

   in 
  this 
  respect 
  is 
  about 
  that 
  between 
  a 
  raptorial 
  and 
  rasorial 
  bird. 
  

  

  As 
  compared 
  with 
  Megalosaurus, 
  Laelaps 
  probably 
  had 
  very 
  short 
  fore 
  limbs. 
  I 
  have 
  

   pointed 
  out 
  the 
  difference 
  in 
  the 
  femur, 
  which 
  is 
  perhaps 
  no 
  more 
  than 
  specific, 
  though 
  

   this 
  cannot 
  be 
  positively 
  asserted. 
  The 
  difference 
  in 
  the 
  form 
  of 
  the 
  extremity 
  of 
  the 
  

   tibia 
  I 
  suspect 
  also 
  to 
  indicate 
  more 
  than 
  specific 
  difference. 
  The 
  bone 
  supposed 
  by 
  

   Owen 
  (Palaeontographical 
  Society) 
  to 
  be 
  scapula 
  furnishes 
  means 
  of 
  estimating 
  the 
  size 
  of 
  

   the 
  humerus. 
  The 
  glenoid 
  cavity 
  is 
  some 
  six 
  inches 
  in 
  diameter, 
  indicating 
  a 
  humerus 
  

   of 
  four 
  times 
  the 
  size 
  of 
  that 
  of 
  Laelaps 
  at 
  least. 
  But 
  this 
  bone 
  is 
  more 
  likely 
  to 
  be 
  an 
  

   ischium 
  than 
  scapula. 
  The 
  claws 
  also 
  of 
  Megalosaurus 
  arc 
  intermediate 
  between 
  those 
  of 
  

   Laelaps 
  and 
  Poecilopleurum, 
  being 
  less 
  compressed 
  and 
  hooked 
  than 
  in 
  the 
  first. 
  

  

  Size. 
  — 
  In 
  estimating 
  the 
  length 
  of 
  this 
  reptile 
  we 
  have 
  the 
  lengths 
  of 
  the 
  limbs 
  and 
  

   tail, 
  and 
  proportions 
  of 
  parts 
  of 
  the 
  jaws 
  to 
  rely 
  on. 
  There 
  is 
  some 
  reason 
  to 
  believe 
  that 
  

   the 
  lengths 
  of 
  the 
  hind 
  leg 
  and 
  the 
  tail 
  were 
  similar. 
  In 
  erect 
  animals, 
  as 
  the 
  Kangaroos 
  

   and 
  Ostrich, 
  the 
  length 
  of 
  the 
  vertebral 
  column 
  anterior 
  to 
  the 
  sacrum 
  about 
  equals 
  the 
  

  

  