THE MICE OF THE FIELD 



in her mouth in turn (her eyes were 

 wonderful), and carried it back to the 

 nest. A few hours later she had shifted 

 family and nest from the south-west 

 corner of the cage to its north-east corner. 

 She had done her best. 



It will be allowed. I think, tlial the 

 difficulties of observing the growth of 

 young Mice under absolutely natural con- 

 ditions are extremely great, if not actually 

 insuperable. Under artihcial conditions 

 something can be done, and the following 

 notes on another Field Mouse family may 

 perhaps be taken as typical of the early 

 stages of Mice in general. 



I have found the growth of infant 

 Meadow Mice, Harvest Mice and Dormice in 

 captivity to proceed on similar lines. 



March 23rd, 1907. Five Long-tailed 

 Field Mice born. The pair (this refers 

 to the father and mother) sit on their 

 family. Infants cling to mother when 

 she jumps. Very small, pink, hairless, 

 semi-transparent, blind, deaf. 



March 28th, 1907. Young Field ]\Iice 

 now blue-grey above (the blue-grey of a 

 dark, clean-shaven man), pink under- 

 neath, feet whitish, still partially trans- 

 parent, hairless, blind, deaf. 



March 31st, 1907. Brownish down 

 visible on head, neck, and shoulders. 

 Ears flattened to the head, but showing 

 the commencement of the 

 conch. Fore-limbs large in 

 proportion. Belly and legs 

 naked. Blind, deaf. Blackish 

 area sharply defined from ])ink 

 flesh of muzzle, where bristles 

 are sprouting. Tail longer, but 

 very short compared with 

 adult's. 



April ist, 1907. Brownish 

 hair (yellowish brindle) every- 

 where e.xcept belly. Still blind 

 and deaf. 



April 3rd, 1907. Mice haired 

 all over ; still blind. 



April 4th, 1907. Mice still 

 blind, but fairly active on 

 their legs. A strong demarca- 

 tion between the sepia of the 

 upper parts and the white of 

 the Icnver. Took one from 

 mother and placed at farther corner of 

 the cage. It headed straight back. By 

 scent ? 



April 7th, 1907. Mice opened eyes. 



There are two interesting points in 

 connection with these notes which are 

 transcribed verbatim. The first is the 

 length of time during which these young 

 creatures remain blind, or at least with 

 their eyelids tight-closed, and the second 

 is the extremely rapid growth of hair 

 when it has once started. 



As a preliminary to considering our 

 British Mice in detail, it will be best, 

 I think, to deal with them shortly as a 

 group, and to point out some simple 

 external differences by which the various 

 species can be distinguished. 



The Mice belong to the vast family of 

 gnawing animals (Rodents). It is a 

 family which embraces perhaps a thou- 

 sand s]:)ecies, but which, in point of 

 individual size, would appear to have 

 passed its prime. There are few, if any, 

 existing rodents that would be a fair 

 fighting match for their ancestors. The 

 paLx'ontologist tells us of a Giant Beaver ; 

 of a Megamys, a " master-great " Mouse 

 as they would }mt it in Suffolk, nearly as 

 large as an ox ; of a Maltese Dormtjuse 

 weightier than a Guinea-pig. It mav be 

 worth recalling that in the case of existing 

 animals whose })edigree is traceable, de- 

 crease of size since prehistoric times is 

 the exception rather than the rule. The 



The 



THE IIAKVKST MOUSK. 

 3-pattcrn of white on the upper lip is characteristic. 



Horse has sjirung fimn a dwarf ancestor; 

 SI) has tlie Rhinoceros ; so has tlie Ele- 

 phant. Huge forms existing in the past 



