The olfactory system of the harbour porpoise is reduced but has a function. The visual system of the harbour porpoise is badly developed, and its inferior to the one of dolphins and human beings. However the acoustic system is highly developed. With the equipment of the speaking centre, the harbour porpoise should be able to speak. The extension of motorical areas demonstrates the high agility of the harbour porpoise. The cytoarchitecture of the motorical fields demonstrate the high efficiency of the motorical system, which is much better developed than the human motorical system. By the important accumulation of free nerve endings, and the large collection of nervous end corpuscles, in the integument, the harbour porpoise has the highest sensibility of all mammals. This is not reflected in the somatosensory areas. The equipment of the somatosensory fields are comparable to those in dolphins and humans.
The study of the structural organization of the limbic cortex of the harbour porpoise confirms the assertion of PORTMANN (1963), and his results are comparable to the findings in other dolphins.
However at present it is not possible to make any declaration about the efficiency of the brain by its neural equipment.