﻿404 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  103 
  

  

  The 
  discovery 
  of 
  this 
  material 
  confirms 
  the 
  suggestion 
  (Simpson, 
  

   1947, 
  p. 
  637) 
  that 
  this 
  group 
  probably 
  migrated 
  to 
  North 
  America 
  

   from 
  Eurasia 
  during 
  the 
  Early 
  Oligocene. 
  Also 
  of 
  interest 
  is 
  that 
  

   the 
  group 
  reached 
  North 
  America 
  before 
  the 
  humerus 
  acquired 
  the 
  

   extreme 
  modification 
  which 
  it 
  has 
  today. 
  

  

  Family 
  Nyctitheriidae 
  

  

  Kentrogomphios 
  strophensis, 
  new 
  genus, 
  new 
  species 
  

  

  Genoholotype.—USl<lM 
  18870 
  (fig. 
  43), 
  facial 
  portion 
  of 
  a 
  skull 
  

   anterior 
  to 
  the 
  cribiform 
  plate, 
  lacking 
  one 
  canine, 
  the 
  crown 
  of 
  the 
  

   other, 
  and 
  the 
  incisors. 
  

  

  Referred 
  material. 
  — 
  USNM 
  18871 
  (fig. 
  44), 
  right 
  mandibular 
  frag- 
  

   ment 
  with 
  M2-3. 
  

  

  Horizon 
  and 
  locality. 
  — 
  ^Lower 
  Oligocene, 
  Chadronian; 
  SWji 
  sec. 
  3, 
  

   T. 
  10 
  N., 
  R.l 
  W,, 
  of 
  the 
  Montana 
  prime 
  meridian, 
  about 
  1 
  mile 
  north 
  

   of 
  Canyon 
  Ferry, 
  Lewis 
  and 
  Clark 
  County, 
  Mont. 
  

  

  Diagnosis. 
  — 
  Portion 
  of 
  skull 
  preserved 
  about 
  the 
  same 
  size 
  as 
  the 
  

   corresponding 
  portion 
  of 
  Scalopus 
  aquaticus; 
  skull 
  elements 
  securely 
  

   fused 
  together, 
  orbit 
  small, 
  infraorbital 
  foramen 
  large 
  and 
  opening 
  

   into 
  a 
  deep 
  elongate 
  pit 
  anterior 
  to 
  orbit, 
  lacrymal 
  duct 
  large 
  and 
  

   situated 
  within 
  the 
  orbit, 
  no 
  palatine 
  vacuities, 
  zygoma 
  believed 
  

   present 
  but 
  very 
  slender, 
  foramina 
  of 
  the 
  alisphenoid 
  region 
  similar 
  

   to 
  those 
  of 
  the 
  Soricidae; 
  I?, 
  Cl, 
  PS?, 
  MS; 
  root 
  of 
  canine 
  elongate- 
  

   triangular 
  in 
  cross 
  section 
  with 
  the 
  acute 
  angle 
  posterior, 
  cusps 
  of 
  

   cheek 
  teeth 
  very 
  high, 
  posterior 
  border 
  of 
  P* 
  to 
  M^ 
  deeply 
  emarginate 
  

   betM^een 
  hypocone 
  and 
  metastyle, 
  no 
  anterior 
  or 
  inner 
  cingulum, 
  

   strong 
  cingulum 
  on 
  hypocone; 
  P^ 
  (if 
  present) 
  minute, 
  single 
  rooted 
  

   and 
  simple 
  ; 
  P^ 
  three 
  rooted, 
  a 
  single 
  outer 
  cusp 
  with 
  a 
  broad 
  shearing 
  

   blade 
  extending 
  posteriorly, 
  deuterocone 
  minute 
  and 
  placed 
  nearer 
  

   the 
  anterior 
  than 
  the 
  posterior 
  edge; 
  P** 
  submolariform, 
  parametacone 
  

   twice 
  as 
  high 
  as 
  protocone, 
  strong 
  metaconal 
  crest, 
  parastyle 
  and 
  

   metastyle 
  strong, 
  external 
  cingulum 
  weak, 
  protocone 
  twice 
  as 
  high 
  

   as 
  hypocone, 
  strong 
  posterior 
  cingulum 
  on 
  hypocone; 
  M^ 
  with 
  para- 
  

   cone 
  and 
  metacone 
  close 
  together 
  and 
  subequal 
  in 
  height, 
  metastylar 
  

   crest 
  strong, 
  parastyle 
  and 
  metastyle 
  well 
  developed, 
  mesostyle 
  ob- 
  

   solete, 
  a 
  small 
  metastylule 
  present, 
  protocone 
  strong 
  and 
  as 
  high 
  

   as 
  paracone, 
  a 
  small 
  protoconule 
  present, 
  hypocone 
  half 
  as 
  high 
  as 
  

   protocone 
  and 
  with 
  a 
  strong 
  posterior 
  cingulum; 
  M^ 
  similar 
  to 
  M*, 
  

   paracone 
  and 
  metacone 
  farther 
  apart, 
  a 
  strong 
  parastylar 
  crest, 
  

   parastyle 
  and 
  metastyle 
  well 
  developed, 
  parastylule 
  and 
  metastylule 
  

   present, 
  a 
  strong 
  mesostyle 
  present; 
  M^ 
  triangular 
  in 
  outline, 
  hypocone 
  

   and 
  metastyle 
  absent, 
  parastyle 
  and 
  parastylule 
  present, 
  a 
  minute 
  

   metaconule 
  present, 
  mesostyle 
  well 
  developed. 
  

  

  