440 MURID^— AGRESTIS 



requires further investigation. M. a. neglectus probably occurs on the 

 coastal islands, having been taken by Sheppard on Bute (see Proc. 

 Zool. Soc, London, 191 3, 833), where it occupies marshy ground south 

 of Kilchattan, and the road-sides in the extreme south of the island. 



Distribution in time : — According to Hinton, M. a. neglectus, or a 

 similar form, appears first in the late pleistocene Fauna of Ightham 

 Fissure, Kent, while M. hirtus is only known in more recent times. 



Description : — This Grass Mouse is as large ^ as its relatives of the 

 islands, differing from exsul chiefly in having, on the average, a simpler 

 Hi} ; besides being much larger than M. hirtus of England it is more 

 heavily furred, and has the upper surface darker and browner. The 

 light bars of the hairs are near "ochraceous buff" approaching tawny, 

 and the resulting colour of the pelage is near " prouts brown," with 

 suggestions of " burnt umber " and " raw umber " ; the under-side 

 is some shade of dull grey, or may be lightly washed with yellowish or 

 " wood brown." A male taken by Sheppard on 24th July 1908, 

 was moulting. 



The skull of young adult and middle-aged specimens is larger than 

 that of M. hirtus, having a condylo-basal length of 25-4 to 26-6 mm. 

 At this stage it resembles that of M. a. exsul of similar size, but has 

 smaller bullae, as in M. hirtus. In old age it attains a condylo-basal 

 length of from 27-5 to 28-1 mm. or more, and the distinction from 

 M. a. exsul in respect of the bullae is less striking. 



The teeth are of the normal form ; ni?- is usually without any trace 

 of the fourth inner angle, but occasionally a vestige of it is present in 

 the larger specimens ; it never attains the size sometimes attained 

 in exsul. 



Dimensions in millimetres: — Immature female, 109 — 37 — 18 — 13; 

 subadult male, 118 — 42 — 17-5 — 12 ; old male, 128 — 40 — 19 — 16. 



Skull: — Condylo-basal length, 25-4 to 28-1 ; breadth, zygomatic, 14-4 

 to i6-i ; inter-orbital, 32 to 3-6; occipital, ii-2 to 12-8; depth, median 

 occipital, 6-2 to 69; length of nasals, 7 to 81 ; of diastema, 7-2 to 8; 

 of mandible, 16 to 17-5; of maxillary tooth -row, 6-5 to 7; of 

 mandibular tooth-row, 6-2 to 6-5. 



Status : — -M. a. neglectus is a little less primitive than the Hebridean 

 exsul in that its m^ is slightly more reduced ; like exsul and the other 

 British sub-species, it is, however, intimately related to the true agrestis 

 of Skandinavia. The differences between them appear mainly to be 

 due to a long-continued segregation. The close relationship of these 

 North British and Skandinavian forms is parallel to that of the Varying 

 Hares, of which Lepus timidus scoticus agrees closely with L. t. timidus 

 of Skandinavia; but there are no Irish Grass Mice to repeat the 

 relationship between L. hibernicus and the extinct pleistocene L. anglicus. 

 ' Miller and other writers never examined full-grown specimens. 



