Some of the fiber bundles associated with the corpus striatum may be studied advantageously in preparations of brains from which fibers of cortical origin have been eliminated. The brains of dogs with congenital absence of the cerebral cortex, or from which the cortex had been removed, have been studied by Holmes,1Edinger,2Morrison,3Papez4and Papez and Rundles.5 The corpus striatum and the thalamus in the monkey have very nearly the same structural pattern as in man, and the results of experimental work on these parts of the brain in the monkey are much more directly applicable to man than results obtained on carnivora. This paper is based on the study of a monkey (Macaca mulatta) from which a large part of the cortex of the right hemisphere had been removed by Dr. H. W. Magoun. The animal was allowed to live for ten months