﻿380 
  

  

  BABCOCK: 
  NEW 
  ENGLAND 
  TURTLES. 
  

  

  Malaclemys 
  centrata 
  concentrica 
  (Shaw). 
  

  

  Diamond-back 
  Terrapin; 
  Chesapeake 
  Terrapin; 
  Terrapin. 
  

  

  Plate 
  26. 
  

  

  Testudo 
  concentrica 
  Shaw, 
  Gen. 
  Zool., 
  1802, 
  vol. 
  3, 
  p. 
  43, 
  pi. 
  9. 
  

  

  Malaclcmmys 
  centrata 
  concentrica 
  W. 
  P. 
  Hay, 
  Bull. 
  U. 
  S. 
  Bur. 
  Fish., 
  1905, 
  vol. 
  24, 
  p. 
  16. 
  

  

  The 
  Diamond-back 
  Terrapin 
  has 
  by 
  far 
  the 
  greatest 
  commercial 
  value 
  of 
  any 
  of 
  the 
  semi- 
  

   aquatic 
  New 
  England 
  turtles. 
  

  

  Size. 
  — 
  The 
  measurements 
  of 
  an 
  adult 
  female 
  from 
  Cos 
  Cob, 
  Conn., 
  in 
  the 
  collection 
  of 
  the 
  

   Boston 
  Society 
  of 
  Natural 
  History 
  are: 
  length 
  of 
  carapace 
  in 
  a 
  straight 
  Une, 
  7^ 
  inches; 
  length 
  

   following 
  curve 
  of 
  carapace, 
  8; 
  width 
  of 
  carapace 
  in 
  a 
  straight 
  Une, 
  5|; 
  width 
  following 
  curve 
  

   of 
  carapace, 
  7; 
  height, 
  2f; 
  sternal 
  length, 
  65; 
  sternal 
  width, 
  4J; 
  nuchal 
  shield, 
  I 
  X 
  ^; 
  length 
  

   of 
  bridge, 
  2\; 
  width 
  of 
  head, 
  \\; 
  length 
  of 
  tail, 
  2. 
  The 
  weight 
  of 
  such 
  a 
  terrapin 
  is 
  about 
  

   two 
  pounds. 
  Large 
  specimens 
  have 
  a 
  total 
  length 
  of 
  10 
  inches 
  or 
  slightly 
  over, 
  but 
  such 
  ani- 
  

   mals 
  are 
  now 
  unconmion. 
  The 
  largest 
  weight 
  record 
  is 
  seven 
  and 
  one-half 
  pounds. 
  The 
  

   length 
  of 
  the 
  carapace 
  exceeds 
  that 
  of 
  the 
  plastron, 
  sometimes 
  slightly, 
  sometimes 
  consider- 
  

   ably, 
  varying 
  with 
  the 
  age 
  and 
  the 
  species 
  of 
  the 
  individual. 
  The 
  following 
  table 
  (after 
  W. 
  P. 
  

   Hay, 
  1905) 
  shows 
  the 
  variations 
  for 
  a 
  number 
  of 
  specimens 
  in 
  this 
  and 
  certain 
  other 
  respects: 
  

  

  Size 
  and 
  Weight 
  of 
  Diamond-hack 
  Terrapins. 
  

  

  Color. 
  — 
  While 
  the 
  coloration 
  is 
  variable, 
  the 
  carapace 
  is 
  usually 
  grayish, 
  with 
  darker 
  

   concentric 
  markings 
  on 
  the 
  shields 
  and 
  at 
  the 
  border. 
  The 
  plastron 
  is 
  yellow, 
  blotched 
  or 
  

  

  