Pain referred to a cutaneous area is one of the commonest complaints heard in any diagnostic clinic. When the reference of pain is over the thorax or abdomen, it is our common habit to think of the possibility of some visceral pathologic state, which, by means of a nervous connection involving the spinal cord, refers itself to the cutaneous surface. The reference of visceral pain through the efferent nervous connections to the spinal cord and its spread therefrom to the cutaneous sensory area supplied by the same cord segment or even to adjoining segments, if the stimulus be of sufficient intensity, has been suggested by the work of McKenzie1, Head2, and Sherren3 and has found wide acceptance throughout medical literature. These cutaneous zones of somatic reference have been described on the basis of embryonic development and charted with a view to their use in diagnosis. Practically, however, it has been shown that they are of relatively little value, and constant relationships between visceral pathologic states and cutaneous manifestations have not been consistent. In general the principle still holds that clinical investigation must first envision the possibility of such an origin of pain, to be excluded only after the most thorough search. Frequently the most careful search will fail to uncover any such visceral basis, and in these the possibility of pain of parietal origin must be considered. Failure to appreciate the possibility of parietal origin for distress may lead to an unwarranted diagnosis of visceral disease with the sequelae of. . .