
THE WATER RAT 485 
extinct, although previously common in the river Stinchar—at first sight 
supports the above supposition. Thompson, however, states that Sin- 
claire found “the ordinary animal much more common,” so that we may 
be here only dealing with melanistic specimens of A. amphibzus proper. 
DIMENSIONS IN MILLIMETRES AND WEIGHT IN GRAMMES :— 

Tail (with- | Hind foot Ear Weight 
Heed and out terminal! (without (greatest in 
y- hairs). claws). length). grammes. 

SexuaLLy IMMATURE MaLEs :— 

Arvicola amphibius amphibius— 
1. West Runton, Norfolk (A. Ruddle), 
19th Sept. 1912 : O eae 130 77 32 13 49 
183 94 22 15 93 
165 111 33 14 1651 
2. Six, Reigate, Surrey (L. E. Adams), 172 117 84 16 1702 
Sept. and Oct. 1913 = 4 175 105 35 15 1703 
175 112 35 18 1804 
185 115 35 17 2185 


SexuaLLy IMMATURE FEMALES :— 



Arvicola amphibius amphibius— 
118 68 29 1l 
1. Three, West Runton, Norfolk (A. 129 83 32 14 
Ruddle), Sept. 1912 > . 135 79 39 15 ne 
155 115 33 15 164 
160 107 32 14 156 
165 103 32 15 163 
2. Seven, Reigate, Surrey (L. E. Adams) 170 108 30 15 1706 
183 103 31 15 195 
185 112 30 15 1756 
185 125 35 15 186 


SEXUALLY MATURE MALES:— 

Arvicola amphibius amphibius— 




185 125 33 3 270 
1. Four, Reigate, Surrey (L. E. Adams), 190 110 34 25 241 
1918. CJ 6 5 5 6 6 190 124 34 17 255 
195 140 35 18 284 
2. Two, Earlsfield, Surrey (C. H. B. 185 110 31 17 = 
Grant), April 1899 . : "5 A 193 128 35 16 ae 
3. Thursley, Surrey (G. Dalgleish, Zoo- 
logist, 1908, p. 194) 5 . . 192 129 36 17 P; 
4. Five, New Forest, Hants (G.S. Miller), 
8rd July 1899 . : 214 111 34 18 
Do. do. 1st July 1899 . = 214 127 88 16 
Do. do. 5th July 1894 . . 219 111 36 174 
Do. do. 9th July 1894 . . 219 132 36 17 
Do. do. 1st Sept. 1894 . . 219 1386 39 18 
5. Exeter, Devon (E. Hollis) . é 7 197 121 33 16 
6. Two, Graftonbury, Hereford (De Win- 
ton), 22nd May 1894. ei ° 2 205 130 81 
Do. do. 21st June 1894 . . 208 106 32 
7. Diss, Norfolk . - : n . 206 139 35 2: 
8. Two,Oundle, Northamptonshire (Cox), { 204 114 32 20 
12th June 1904 ; é 5 . i 208 125 29 18 
r 2 
9. Four, Read’s Island, River Humber a iy ee is 
(Capt. D. E. Hume), 28th Feb. 1896 194 197 39 19 
Do. do. 28th March 1896. 207 140 37 15 
10. Waith Beck (G. H. Caton Haigh), 18th 
May 1895 s C ° @ * 210 118 36 a 
Averages : a . C 201°3 124 84 15°8 a 
1 Testis 4 mm. in diameter. 2 Testis 4 mm. in diameter. 3 Testis 5 mm. in diameter. 
4 Testis 9 mm. in diameter. 5 Testis 5 mm. in diameter. 
_,, ,All these specimens were born in the year of capture. (Adams.) 
6 With the exception of these two specimens all were imperforate ; all were born in the year of capture; 
and none (including the perforate specimens) would breed before the following spring. (Adams.) 
