MAMMALS It is unfortunately the case that until a few years ago the mammals of Hertfordshire had received but little attention from local naturalists. It seems that until recently no records whatever were kept of the occur- rence of rare species or varieties, and it is now when all information that can be collected is necessary for the compilation of a satisfactory list of the mammals of the county that this neglect of former years is especially felt. It will therefore be readily understood that with merely the records and notes of the past few years at hand the following list is of necessity very limited, and that the record of extinct species or of those which are becoming so can scarcely be given. The chief sources from which I have procured information are the Transactions of the Watford Natural History Society and the Transactions of the Hertfordshire Natural History Society ; I have also found some interesting records in Mr. Harting's articles on British Mammals which have appeared from time to time in the Zoologist. Of the several branches the Cheiroptera have received the least amount of attention. Only four species of bats have up to the present been identified, and it is reasonable to suppose that wken more time and trouble have been given to them, several species which are found in other counties will be added to the list. The distribution of the various mammals has by no means been thoroughly worked out, so that in the case of some it is impossible to say more than that they are to be found in the county, without reference to the localities in which they most frequently occur. There is little of special interest that can be said about the majority, as they are common throughout the county, but to such animals as the badger (Meles me/es), the polecat (Putorius putorius], the pine marten (Mustela martes], and the otter (Lutra /utra), especial interest is attached owing to their declining numbers and rare occurrence at the present day. Unfortunately full notes only concerning the first-named are to hand, and for these I have to thank Dr. Brett and Mr. T. Vaughan Roberts from whose respective pens most interesting and valuable notes on this species have appeared at intervals in the Trans, of the Hertfordshire Nat. Hist. Soc. At the end of the list will be found the mention of two animals, the red deer (Cervus elapbus) and the fallow deer (Ceruus dama), which appear in the county at the present day only in a semi-domesticated state, and are not actually feree naturae. These have been included, for I consider that they are practically a link between the past and the present, since these animals were no doubt at one time to be found in a wild state in Hertfordshire, as 217