Nebria brevicollis (F.) and Philonthus decorus (Grav.) are two of the commonest predaceous insects of the woodland floor, and the head structure, mouthparts and feeding methods of each have been compared and contrasted. In N. brevicollis, the mandibles are well developed for the capture and shearing of the prey, whilst the laciniæ of the maxillæ form rakes which pull the food towards the cibarium across the smooth labium. Food is bolted in large pieces and stored in the crop before passing through the filtering and grinding gizzard. A fundamental difference between the two beetles is seen in the movements and structure of the maxillæ, and a mechanism whereby stipital abduction and protraction is effected in N. brevicollis has been proposed. In P. decorus, the mandibles are also developed for prey capture but hold the prey between large brushes while it is being crushed. The maxillæ form thick brushes which also hold the prey, and the labium-hypopharynx is densely covered with setæ which prevent the entry of solid food into the mouth. Thus, in contrast to N. brevicollis, the labrum has a median food groove which directs the food upwards and away from the mouth, and returns it to the mandibles to be re-chewed. Here, partial external digestion occurs and fluid food is sucked in by the powerful cibarial pump, and passed to the filtering proventriculus. In order to show how the two feeding methods described fit into the general pattern, the feeding methods of various predaceous Coleoptera have been reviewed in relation to different types of gut structure.