﻿MACHAEROIDES 
  EOTHEN 
  MATTHEW 
  GAZIN 
  337 
  

  

  Inasmuch 
  as 
  it 
  seems 
  advisable 
  to 
  exclude 
  the 
  Limnocyoninae 
  

   from 
  the 
  Oxj-'aenidae, 
  and 
  since 
  I 
  am 
  unable 
  to 
  reconcile 
  it 
  with 
  

   the 
  Hyaenodontidae 
  on 
  the 
  basis 
  of 
  carnassial 
  differentiation, 
  I 
  

   propose, 
  at 
  the 
  risk 
  of 
  censure, 
  that 
  the 
  Limnocyoninae 
  and 
  

   Machaeroidinae 
  be 
  given 
  family 
  recognition 
  as 
  the 
  Limnocyonidae, 
  

  

  Description 
  of 
  skull 
  (pi. 
  45) 
  . 
  — 
  The 
  skull 
  of 
  Machaeroidcs 
  eothen 
  

   is 
  significantly 
  smaller 
  than 
  that 
  of 
  Limnocyori 
  verns 
  but 
  much 
  

   larger 
  than 
  Thinocyon 
  vclox, 
  corresponding 
  closely 
  in 
  size 
  to 
  

   Siyiopa 
  rapax 
  among 
  its 
  less 
  closely 
  related 
  contemporaries. 
  The 
  

   skull 
  is 
  moderately 
  slender 
  but 
  with 
  a 
  noticeably 
  deep 
  rostrum, 
  

   high 
  srgittal 
  crest, 
  and 
  a 
  narrow 
  occiput. 
  

  

  The 
  rostrum, 
  in 
  addition 
  to 
  depth, 
  exhibits 
  a 
  well-inflated 
  

   maxillary 
  portion 
  covering 
  the 
  long 
  root 
  section 
  of 
  the 
  canine, 
  

   extending 
  parallel 
  and 
  immediately 
  posterior 
  to 
  the 
  suture 
  join- 
  

   ing 
  the 
  premaxilla. 
  The 
  nasals 
  extend 
  posteriorly 
  in 
  a 
  nearly 
  

   F-shaped 
  wedge 
  between 
  the 
  frontals, 
  terminating 
  fully 
  as 
  far 
  

   back 
  as 
  the 
  postorbital 
  processes. 
  In 
  Thinocyon 
  and 
  Limnocyon 
  

   the 
  nasals 
  as 
  exposed 
  terminate 
  distinctly 
  forward 
  of 
  this 
  position. 
  

   The 
  postorbital 
  processes 
  of 
  the 
  frontals 
  are 
  moderately 
  well 
  

   developed 
  and, 
  although 
  possibly 
  not 
  complete, 
  do 
  not 
  appear 
  so 
  

   prolonged 
  as 
  in 
  Thinocyon. 
  The 
  lachrymal 
  bone 
  in 
  M. 
  eothen 
  is 
  

   lar;;e 
  and 
  extends 
  well 
  forward 
  of 
  the 
  orbit 
  and 
  exhibits 
  a 
  most 
  

   unusual 
  feature 
  in 
  that 
  the 
  lachrymal 
  foramen 
  enters 
  the 
  skull 
  

   anterior 
  to 
  the 
  orbital 
  rim 
  and 
  anteroventral 
  to 
  the 
  lachrymal 
  

   crest 
  or 
  tubercle. 
  A 
  smaller 
  foramen 
  also 
  enters 
  the 
  lachrymal 
  

   bone 
  outside 
  and 
  immediately 
  dorsal 
  to 
  the 
  lachrymal 
  tubercle. 
  

   This 
  arrangement 
  was 
  not 
  ob.-.erved 
  in 
  other 
  creodonts, 
  but 
  it 
  

   occurs 
  in 
  marsupials 
  and 
  sloths. 
  Matthew, 
  " 
  however, 
  noted 
  that 
  

   the 
  lachrymal 
  foramen 
  in 
  Limnocyon 
  was 
  very 
  near 
  the 
  orbital 
  

   rim. 
  

  

  The 
  cranial 
  portion 
  of 
  the 
  skull 
  is 
  characterized 
  by 
  an 
  exceed- 
  

   ingly 
  small 
  brain 
  case, 
  relatively 
  much 
  smaller 
  than 
  in 
  Thinocyon, 
  

   and 
  a 
  very 
  high 
  sagittal 
  crest, 
  which 
  joins 
  a 
  high 
  but 
  narrow 
  

   occipital 
  crest. 
  The 
  latter 
  is 
  overhanging 
  but, 
  quite 
  unlike 
  Lim- 
  

   nocyon, 
  is 
  noticeably 
  constricted 
  transversely 
  immediately 
  above 
  

   the 
  occipital 
  condyles. 
  A 
  prominent 
  vascular 
  foramen 
  is 
  noted 
  

   at 
  the 
  suture 
  between 
  the 
  parietal 
  and 
  squamosal 
  at 
  a 
  position 
  

   about 
  over 
  the 
  trough 
  for 
  the 
  audital 
  tube, 
  and 
  one 
  also 
  in 
  the 
  

   posterior 
  portion 
  of 
  the 
  temporal 
  fossa, 
  presumably 
  at 
  about 
  the 
  

   juncture 
  of 
  the 
  parieto-squamosal 
  and 
  parieto-occipital 
  sutures. 
  

  

  In 
  ventral 
  aspect 
  the 
  palatal 
  portion 
  of 
  the 
  skull 
  shows 
  no 
  

   unusual 
  features. 
  No 
  evidence 
  exists 
  of 
  the 
  grooves 
  and 
  ridges 
  

  

  • 
  Matthew. 
  W. 
  D 
  , 
  ibid., 
  p. 
  438. 
  

  

  