=233. Formation and vegetation maps= are detailed maps of a single formation or a series of them, showing the formational limits, and when the scale is not too small, the ecotones of zones and consocies. In the cases where the topography is level, as sometimes happens in mapping single formations, the chain and pedometer must be used to ascertain the size of the different areas. Indeed in all mapping of vegetation, the methods of surveying are directly applicable. Over large areas, however, it is not necessary that limits be drawn with mathematical accuracy, and for the purposes of the ecologist, the plane table and camera are satisfactory substitutes for the surveyor’s transit, at least in the present aspect of the subject. When the formation or group of formations is commanded by an elevation of some height, the latter is used as a base. A plane table is established upon it and the topographical and vegetational features are recorded in the usual way. This map is usually supplemented by a series of views from the same base. Indeed it has come to be recognized that a complete series of photographs of this kind give a more valuable record than the plane table, and that the construction of an accurate map from them is an easy matter. Since the camera saves much time and energy also, it is used almost exclusively to furnish the data for map making. In hilly, and especially in mountainous regions, the photographic method is indispensable. Its application is extremely simple. A central hill or mountain is selected, and from it a series of views is taken so that the edge of one exactly meets the edge of the other. This is an extremely important matter, and demands much nicety of judgment. The camera is kept in the same spot, and after each exposure it is turned as the operator looks through it until a landmark at one edge just passes from view at the other. As soon as the new position is determined, the tripod screw is turned to hold the box firmly in position. In case of a slight jar, the exact position should again be obtained. If the series is accurately made, the resulting prints will give a complete panoramic view of the region, without overlap or omission. For this purpose, a 6½ × 8½ camera is desirable, since the topographic and vegetational features are larger and stand out more distinctly. A large camera requires fewer changes of position, and hence saves time and reduces the chance of error. A 4 × 5 camera serves the purpose sufficiently well, though it requires a little more care in operation on account of the greater number of exposures necessary. This may be avoided in some degree by the use of a wide-angle lens if the depth of the area is not too great. Whatever camera may be used, a telephoto lens is a very desirable adjunct, since it enables one to choose between three different sizes of the view without changing the position of the camera. To avoid possible confusion, the exposures are