12 Herbarium of slides, Catalogue entries and paleographs for each number is noted also in the list. Clarifying information has been added to the description of some slides; information which is bracketed is speculative or specifically not derived the source materials described above. B) A DIATOM EXSICCATI COLLECTION The algal herbarium which the Boston Society of Natural History donated to the Farlow Herbarium in 1941 contained 303 sheets of diatom exsiccati that I have determined to have come from Bailey and to represent materials described in the second part of the 1857 bequest. Most of these sheets bear specific notations in Bailey's handwriting. I have attributed other sheets to his bequest because they represent specimens from collectors, such as Brébisson, Lenormand, Dickie and Ralfs, with whom Bailey exchanged materials extensively and because I have found no evidence that they entered the Society's collection by a means other than Bailey. The 303 sheets from Bailey's herbarium were part of a slightly larger collection of diatom exsiccati donated by the Society; upon receipt of these materials by the Farlow Herbarium, all sheets in the collection were pinned or glued to larger herbarium sheets and thus their arrangement was largely fixed. I have numbered all the exissicati in this collection and prefixed each number with an "E", e.g. E131; each number has been placed on a round, 0.8 cm diameter, white label on the sheet. The numerical series describing the exsiccati approximates an alphabetical arrangement of the taxa. Numbers not listed in this series in the index correspond to non-Bailey diatom exsiccati. The authors of taxa names presented in the list are those given on the original exsiccati labels. C) A COLLECTION OF UNMOUNTED MATERIALS comprising bottles of original material and slides derived from them.