566 MURIDA—MICROMYS 
an ounce avoirdupois.... A full-grown mus medius domesticus [i.e. 
sylvaticus*], weighs, I find, one ounce lumping weight, which is more 
than six times as much.” The weight thus indicated by White 
equals about 4-7 grammes. The weights recorded by other observers 
are:—Edward, Banff (see p. 559), } ounce, 13 grains=4-38 grammes ; 
“an old one”? is said to have weighed 1 drachm, 5 grains=2-09 
grammes; another*® “scarcely exceeds a drachm,” or 1-77 grammes. 
The two last examples were probably immature nestlings, and the 
others can hardly have been fully mature, because Owen (Azaz. of 
Vertebrates, iti., 143) gives the weight of a specimen which he dissected 
as 112 grains, or about 7-25 grammes. In this individual the brain 
weighed 6 grains, or nearly -39 gramme; in a House Mouse weighing 
327 grains, or nearly 21-2 grammes, the brain weighed no more. 
Skull: — Condylo-basal length, 16 to 17:8; zygomatic breadth, 
g to 9-6; inter-orbital constriction, 3 to 3:2; brain-case, breadth, 
8-6 to 9-6, depth at middle, 5-2 to 6-2; length of nasals, 5-4 to 6; of 
diastema, 3-9 to 4:6; of mandible, 9 to 10; of maxillary tooth-row, 
2-6 to 3; of mandibular tooth-row, 2-6 to 2-8 mm. 
Distinguishing characters:—-The Harvest Mouse is readily dis- 
tinguishable among British murines by its small size, bright reddish 
dorsal tints, and sharply contrasted white belly; its blunt short nose 
(somewhat recalling that of a young Bank Mouse); and by the char- 
acters of the ears, hands, feet and prehensile tail, as described above. 
The Harvest Mouse presents us with many points of 
interest. Not only is it one of the prettiest and smallest of 
British mammals, but it is a highly specialised mammal, fitted 
by its structure for life amongst beds of strong grass, reeds, 
or corn, and living on a diet of seeds and insects. It is, con- 
sequently, a very acrobatic creature, light enough to poise 
itself on a head of corn, and a nimble climber amongst the 
stalks. It is a fine gymnast; at times it revolves* vertically, 
horizontally, or at an angle, balancing itself or helping a 
descent with its slightly prehensile tail®; but it is not as fast 
1 Or more probably in this case 4. f. wintoni; for White gives the lengths of 
head and body and tail as 4} inches (108 mm.) each, the weight mentioned being 
nearly 29 grammes. 
2 Knapp, Journal of a Naturalist, 139 ; cited in Zoologist, 1843, 292. 
3 W. Hewett, Zoologist, 1843, 349. 
1D. English, Some Smaller British Mammails (undated), 81. 
5 G. T. Rope, of. cit, 1884, 58, has repeatedly seen one supporting the weight of 
its body on the tail for a second or so in trying to climb out of an upright glass jar, 
the fore paws merely balancing the animal’s weight against the glass. Millais has 
seen them hang free by the tail, but it cannot swing or hang thus for any length of time. 
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