﻿654 
  PROCEEDINQS 
  OF 
  THE 
  NATIONAL 
  MUSEUM. 
  vol.44. 
  

  

  Although 
  much 
  has 
  been 
  written 
  of 
  the 
  zeuglodons 
  by 
  various 
  

   investigators 
  who 
  have 
  compared 
  in 
  detail 
  its 
  various 
  anatomical 
  

   features 
  and 
  discussed 
  at 
  length 
  its 
  relationships, 
  there 
  still 
  exists 
  

   wide 
  difference 
  of 
  opinion 
  among 
  authorities 
  regarding 
  the 
  true 
  affin- 
  

   ities 
  of 
  the 
  group. 
  One 
  point 
  of 
  weakness 
  in 
  all 
  these 
  discussions 
  is 
  

   the 
  absence 
  of 
  any 
  known 
  intermediary 
  forms 
  to 
  connect 
  them 
  with 
  

   any 
  of 
  the 
  other 
  groups 
  to 
  which 
  they 
  may 
  seem 
  aUied. 
  

  

  As 
  has 
  been 
  pointed 
  out 
  by 
  various 
  authors/ 
  the 
  zeuglodons 
  possess 
  

   many 
  primitive 
  characters, 
  especially 
  in 
  the 
  skull 
  and 
  teeth, 
  in 
  which 
  

   they 
  resemble 
  either 
  the 
  seals 
  or 
  the 
  more 
  ancient 
  creodonts. 
  In 
  

   other 
  characters, 
  the 
  ones 
  in 
  which 
  they 
  are 
  more 
  highly 
  specialized, 
  

   they 
  resemble 
  the 
  whales 
  in 
  some 
  respects 
  ; 
  while 
  in 
  others, 
  as 
  in 
  the 
  

   modification 
  of 
  the 
  arm, 
  they 
  suggest 
  the 
  sea 
  lions. 
  There 
  is 
  nothing, 
  

   however, 
  to 
  warrant 
  placing 
  them 
  in 
  any 
  intermediate 
  position 
  

   between 
  these 
  at 
  present 
  widely 
  separated 
  groups 
  of 
  mammals, 
  for 
  

   at 
  the 
  time 
  of 
  their 
  apparent 
  extinction 
  in 
  the 
  Eocene 
  they 
  had 
  

   already 
  outstripped 
  in 
  the 
  development 
  of 
  certain 
  important 
  modifi- 
  

   cations 
  what 
  has 
  been 
  accomplished 
  by 
  any 
  of 
  the 
  modern 
  cetaceans, 
  

   hence 
  could 
  not 
  have 
  stood 
  in 
  any 
  direct 
  ancestral 
  relationship 
  to 
  

   the 
  latter, 
  while 
  the 
  primitive 
  features 
  which 
  they 
  retained 
  are 
  too 
  

   generalized 
  in 
  character 
  to 
  especially 
  connect 
  them 
  with 
  any 
  of 
  the 
  

   more 
  archaic 
  groups 
  of 
  mammals. 
  Furthermore, 
  there 
  is 
  at 
  present 
  

   too 
  much 
  obscurity 
  concerning 
  the 
  origin 
  of 
  the 
  whales 
  to 
  arrive 
  at 
  

   anytliing 
  definite 
  regarding 
  the 
  derivation 
  of 
  the 
  zeuglodons 
  from 
  

   any 
  ancestral 
  form 
  of 
  that 
  group. 
  

  

  The 
  high 
  degree 
  of 
  specialization 
  which 
  they 
  had 
  attained 
  in 
  the 
  

   development 
  of 
  the 
  body 
  and 
  limbs, 
  combined 
  with 
  the 
  retention 
  of 
  

   so 
  many 
  primitive 
  characters, 
  would 
  indicate 
  a 
  very 
  ancient 
  origin 
  

   for 
  these 
  animals, 
  and 
  if 
  derived 
  from 
  the 
  same 
  stock 
  as 
  the 
  seals 
  or 
  

   sea 
  lions 
  or 
  direct 
  from 
  the 
  early 
  creodonts, 
  then- 
  branching-off 
  point 
  

   must 
  have 
  dated 
  back 
  to 
  a 
  time 
  most 
  remote, 
  certainly 
  before 
  the 
  

   various 
  natural 
  groups 
  of 
  the 
  creodonts 
  appearing 
  in 
  the 
  early 
  

   Eocene 
  were 
  sufiiciently 
  differentiated 
  to 
  be 
  recognized. 
  

  

  I 
  See 
  Thompson, 
  On 
  the 
  Systematic 
  position 
  of 
  Zeuglodon, 
  Univ. 
  Dundee, 
  June, 
  1890; 
  Dames, 
  Paleont. 
  

   Abhandl., 
  1894, 
  pp. 
  189-219; 
  Zittel, 
  Grimdzuge 
  der 
  Paleont.; 
  and 
  others. 
  

  

  