15 such criteria as ones of "geographical coincidence." I have limited the inclusion of materials in this part of the collection, as in the whole collection, to those I am confident were included in the 1857 bequest. I have prepared several indices to the Bailey Collection. The taxa index includes all generic and species names of diatoms 1) recorded on the slides, in the Catalogue of the Bailey Microscopical Collection and in the paleographs, 2) noted on sheets of exsiccati, not just the original names applied by the collectors, and 3) listed in the Catalogue of the Unmounted Materials [of the] Bailey Collection for which there are extant materials in the collection at the Farlow Herbarium. The gographical and person's indices cover also all appropriate names used in the three major parts of the collection, plus a few I have added to facilitate access to selected materials.