The State of New York has the largest area of any northern State east of Michigan. It also possesses a great diversity of surface, with its two mountain ranges, its numerous lakes, its interior salt basin, and its seashore confined entirely to the southern extremity. On its eastern side it stretches through more than four degrees of north latitude, and as these are the degrees just south of the 45th parallel, it is easy to understand that there is liable to be a greater intermixture of northern and southern forms of ferns than there would be in a State lying farther south. And the fact is that certain species from the north and others from the south do meet within its borders. This also accounts for the large number of species found in the State: California and Texas, the one State having four times the area of New York, and the other five times that area, being the only ones which contain as large or a larger number of species. For the purpose of fern classification, the State may be divided into four distinct zones, as follows: I. The Littoral.—This comprises Long Island and Staten Island. Only one fern is peculiar to this zone, viz. _Woodwardia angustifolia_; but there are two Lycopods, viz. _L. alopecuroides_ and its variety _adpressum_. II. The Catskill Mountain Region, extending down to Manhattan Island.—This being the southern mountain range of the State, it is here that three southern species find their northern limit, viz. _Asplenium Bradleyi_, _A. montanum_ and _Cheilanthes vestita_. It may be a question whether the Connecticut stations for _Asplenium montanum_ lie farther north than the New York stations, but it is certain that there can be but little difference between them in this respect. III. The Adirondack Region, extending as far south as Little Falls.—Here there are a few of the northern species that descend to their southern limit in this country. Among them may be mentioned _Nephrodium fragrans_, _Polystichum Braunii_, _Woodsia glabella_, and _W. hyperborea_. There are also two Lycopods to be included in this list, _L. annotinum pungens_ and _L. Sitchense_. IV. The Western Region, extending from the mountain regions to the State’s western boundary, the southern part drained by the Susquehanna and its tributaries, and the northern part containing (a) _The Salt Basin_ of Syracuse and its vicinity, the home of _Scolopendrium_ and _Botrychium Onondagense_, and (b) _The Central Basin_, extending from Little Falls to Oneida Lake, and drained by the Mohawk River, being famous for its large number of _Botrychia_, some of which seem to be almost, if not quite, peculiar to this region.