﻿460 
  Mr. 
  0. 
  Thomas 
  on 
  

  

  zygomatic 
  breadth 
  18*2 
  ; 
  breadth 
  of 
  brain-case 
  15*3 
  ; 
  ante- 
  

   rior 
  palatine 
  foramina 
  7*2 
  ; 
  posterior 
  palatine 
  foramina 
  43 
  ; 
  

   upper 
  molar 
  series 
  5'4. 
  

  

  llab. 
  and 
  Type 
  as 
  above. 
  

  

  This 
  gerbil 
  is 
  most 
  like 
  the 
  Soudanese 
  T. 
  butleri. 
  Wrought., 
  

   being 
  distinguished 
  from 
  T. 
  gracilis 
  by 
  its 
  greater 
  size 
  and 
  

   from 
  T. 
  lacustris 
  by 
  its 
  darker 
  colour, 
  these 
  being 
  the 
  only 
  

   West-African 
  species 
  hitherto 
  known. 
  

  

  The 
  Museum 
  also 
  contains 
  a 
  young 
  specimen 
  of 
  the 
  same 
  

   species 
  collected 
  at 
  Yola 
  by 
  Mr. 
  Gr. 
  W. 
  Webster. 
  

  

  8. 
  Arvicanthis 
  mordax, 
  sp. 
  n. 
  

  

  <J. 
  3, 
  11 
  (young) 
  ; 
  ? 
  . 
  12. 
  Panyam, 
  4000'. 
  

  

  Near 
  A. 
  rujinus, 
  Temra., 
  but 
  greyer 
  and 
  teeth 
  larger. 
  

  

  Size 
  large, 
  as 
  in 
  A. 
  rujinus. 
  General 
  colour 
  decidedly 
  

   greyer 
  than 
  in 
  rujinus, 
  the 
  head 
  and 
  fore-back 
  more 
  buffy 
  

   than 
  " 
  drab-grey," 
  the 
  tips 
  of 
  the 
  hairs 
  cream-buff, 
  their 
  

   blackish 
  slaty 
  bases 
  showing 
  through. 
  Hind-back 
  and 
  rump 
  

   gradually 
  approaching 
  " 
  russet." 
  Base 
  of 
  tail 
  russet. 
  Under 
  

   surface 
  dull 
  greyish, 
  the 
  tips 
  of 
  the 
  hairs 
  varying 
  from 
  

   greyish 
  white 
  to 
  drab. 
  Hands 
  and 
  feet 
  dull 
  buffy. 
  Tail 
  

   more 
  heavily 
  haired 
  than 
  in 
  rujinus 
  ', 
  blackish 
  above, 
  buffy 
  

   on 
  sides 
  and 
  below. 
  

  

  Skull 
  very 
  similar 
  to 
  that 
  of 
  A. 
  rujinus, 
  but 
  somewhat 
  

   greater 
  in 
  zygomatic 
  spread, 
  the 
  length 
  being 
  about 
  the 
  same. 
  

  

  Incisors, 
  as 
  in 
  A. 
  rujinus 
  , 
  very 
  broad 
  and 
  heavy. 
  Molars 
  

   markedly 
  broader 
  than 
  in 
  that 
  species. 
  

  

  Dimensions 
  of 
  the 
  type 
  (measured 
  in 
  flesh) 
  : 
  — 
  

  

  Head 
  and 
  body 
  164 
  mm. 
  ; 
  tail 
  147 
  ; 
  hind 
  foot 
  34; 
  ear 
  22. 
  

  

  Skull: 
  greatest 
  length 
  40; 
  condylo-incisive 
  length 
  38'2 
  ; 
  

   zygomatic 
  breadth 
  20'3; 
  nasals 
  15*3; 
  interorbital 
  breadth 
  G'l 
  ; 
  

   palatilar 
  length 
  18*3 
  ; 
  palatal 
  foramina 
  &2 
  ; 
  upper 
  molar 
  

   series 
  7*6 
  ; 
  breadth 
  of 
  m 
  1 
  24. 
  

  

  J 
  fab. 
  as 
  above. 
  

  

  Type. 
  Old 
  female. 
  B.M, 
  no. 
  11, 
  3. 
  24. 
  11. 
  Original 
  num- 
  

   ber 
  12. 
  Collected 
  14th 
  September, 
  1910. 
  

  

  This 
  is 
  no 
  doubt 
  the 
  N.-Nigerian 
  representative 
  of 
  

   A. 
  rujinus, 
  from 
  which 
  it 
  differs 
  by 
  its 
  greyer 
  colour 
  and 
  

   larger 
  molars. 
  

  

  A 
  specimen 
  of 
  it, 
  without 
  skull, 
  was 
  also 
  obtained 
  during 
  

   the 
  Alexander-Gosling 
  Expedition 
  by 
  the 
  late 
  Capt. 
  Boyd 
  

   Alexander 
  at 
  Ibi, 
  on 
  the 
  Benue, 
  in 
  1904. 
  

  

  