The anatomical description of the hypothalamo-hypophysial system of the White-crowned Sparrow, Zonotrichia leucophrys gambelii, as presented in this treatise, is by no means of definitive nature. Research in this area, in our own laboratories and elsewhere, continues at such a pace and is sufficiently in flux as to preclude the possibility of definitive morphological and functional conclu sions at this time. Nevertheless, we do believe that there is now some genuinely heuristic value in a presentation of our neuroanatomical material. Most of this material is derived from the above-mentioned...