ON A NEGLECTED SPECIES OF FIELD MOUSE. 443 



distinct line of demarcation, give this mouse a peculiarly striking 

 appearance ; it is almost as beautiful as a Squirrel. Its large 

 ears and wide-open prominent eyes, its long tail, and hind feet 

 are fully as much developed in proportion to its size as in Mas 

 sylvaticus, consequently the measurements are greater. 



Now as to its structural peculiarities. The tail is made up 

 of 30 vertebras, whereas in sylvaticus I have never found more 

 than 27. In the skull the differences are not easy to describe — 

 the measurements being so minute — and are hard to work out, 

 owing to the difference in the size of the respective skulls; but 

 the skull of M. flavicollis is readily distinguished from that of its 

 near ally by its greater length, which is usually 29 mm. in the 

 perfectly clean skull. This may be only in proportion to the 

 larger size of the animal, but it is a longer-, narrower-, stronger- 

 looking skull; the point of the nasal bones where they join the 

 frontal is sharper, and — what is a far better character — the angle 

 of the suture of the frontal and parietal bones is more acute ; the 

 superciliary ridges are well developed, while in sylvaticus they 

 are hardly noticeable even in the oldest individuals. The orbito- 

 temporal fossa, or all the space between the zygoma and the skull, 

 is longer and narrower; looking at the skull from above and 

 behind, and likening it to a vase, the " shoulders" are much more 

 sloping. The dentition is the same as in M. sylvaticus. 



The bright fawn-coloured band across the chest distinguishes 

 M. flavicollis at all ages and in all seasons, though in the plum- 

 bous-coloured young naturally the colour is not so bright ; still 

 the more or less chestnut-tinged dark band is quite noticeable in 

 the smallest mouse that is ever likely to be caught in a trap. 



The general habits of this mouse are similar to those of 

 sylvaticus ; there may be slight differences, but I am not prepared 

 just now to fix them. 



The distribution of this mouse seems to be very local, 

 and the localities in which it occurs are widely separated, not 

 occurring, so far as I know, apart from sylvaticus, yet never 

 crossing, as I believe, or even mixing with that species. 



At first I was inclined to describe this mouse as peculiar to 

 Herefordshire, it being particularly abundant around Grafton- 

 bury in this county, and also at Bishopstone in the same county, 

 where, in 1885, three specimens, now in the National Collection, 

 were obtained by Mr. H. N, Ridley. 



2m2 



