b, sheltered coast; 3, exposed surfaces. 2, semi-exposed surfaces. 1, fully protected surfaces. Guiler realises that there must be a wide margin in estimates according to the personal opinions of different workers. A protected situation on his view is one where waves never exceed 6 inches (5 cm.) in height. It is almost impossible to give a precise definition here, since in the present writer's experience one spot may come under the category of being protected when wind is off the land, and the same place would be classified as semi- or even fully exposed when a gale blows from the opposite direction. From this point of view Moore's exposure factor based on percentage of wind direction would be more satisfactory. Despite these drawbacks, Guiler's scheme is considered suitable for application here (Table I). The Beaufort Scale is given as that estimated at the time of examination of each locality. Where a range of variation in wind strength is known, figures are not given in brackets since they do not represent an annual range (except for Narrow Neck). Further, most visits were made under comparatively favourable weather conditions, and so maximum wind strength is not known. From a quick glance at a given formula it is not always easy to recall which figure represents which factor. This suggests an improvement to Guiler's setting out of the formula by inserting the factor symbols M, W, D and T before their respective figures, as in the formulae for Hauraki Gulf stations in Table I. Part II.—Terminology and Biotic Communities Terminology The nature and status of the various terms in most general use to cater for the requirements of rocky shore ecology are still the subject of much controversy. After consideration of many coasts in both hemispheres, T. A. and Anne Stephenson (1949) proposed a fresh series of basic terms to replace their former (1943, 1947) suggestions. These, they hope, may prove to have some degree of universal application. For their previous Littorina and balanoid zones and sublittoral fringe they would now substitute the midlittoral zone which separates the supralittoral from the infralittoral zone. Womersley and Edmonds (1952), on the other hand, argue that the Stephensons' schema requires modification in respect to the South Australian rocky coasts. As far as New Zealand is concerned, Chapman and Trevarthen (1952) have re-affirmed, and the writer also holds this opinion, that the Stephensons' scheme is more readily applicable than any other yet proposed to categorize its hard rock coastline. This scheme, which has already been accepted favourably by other workers (e.g., Guiler, 1949, Lewis, 1953, Knox, 1953) can be tested in the light of local behaviour of intertidal organisms. 1. Supralittoral Zone The supralittoral zone appears to be a valid entity in those parts of the Hauraki Gulf where cliffs tower above the midlittoral. However, in places where land communities advance over low-lying areas to a point directly above E.H.W.S. it may be eliminated. Against this it can be argued that such usually happens only behind sandy beaches or mudflats where, as Chapman and Trevarthen (loc. cit.) have emphasized, zonation is governed largely by a different combination of factors. Takapuna Reef, north of Narrow Neck, provides an instance where there is no true supralittoral zone.