The described species of Murdochia are 13 in number (Powell, 1946) and seem to have a rather localised distribution in New Zealand rain-forests. The species most commonly encountered near Auckland is M. pallidum (see Suter, 1913); it is 5 mm. in length, 3·25 mm. in greatest diameter, turbinate, conical, horny brown in colour, with the operculum silvery-white (Text-fig. 1). The most typical habitat is in the deep, ensheathing leaf bases of Rhopalostylis, and also of Collospermum and Freycenetia. Pfeiffer's term “cryptozoic” admirably describes the mode of life of these animals, avoiding the light and seeking moisture. This fauna includes a wide range of small invertebrates, such as pulmonate snails (flammulinids), slugs (Athoracophorus), arachnids and myriapods, and insects—especially coleoptera and collembola. Most of these are vegetarians, taking into the gut fragments of food of varied detrital nature, including pieces of decaying leaves and wood pulp, and much unrecognisable plant material. In many cases, including Murdochia, a high proportion of the food is made up of fungal mycelia scraped off the moist substratum with the radula. M. pallidum seems to be more or less a specialist in its diet, and a similar preference for fungi is reported in the case of the tropical American cyclophorids (de la Torre, Bartsch, and Morrison, 1942). Text-Fig. 1—The operculum, uppen surface. The animal when removed from the shell is found to be quite unspecialised in its structure. The foot is long, truncate, and squarish in front, rounded behind. The margin of the sole is surrounded by a wide strip of black-pigmented epithelium, thrown into small, regular, puckered folds; the central tract of the plantar surface is covered with short-celled smooth epithelium, deeply enfolded in the middle of the sole to give exit to the secretion of the pedal gland. Other sources of mucous secretion are present, in the mantle cavity—a broad hypo-