PREFACE. Vil 
during a visit of agricultural exploration in Colombia. As much of © 
the literature of the palms is based on rather fragmentary information, 
these more complete data, drawn from fresh material, will be appre- 
ciated. One of the results of the present study is to show the desira- 
bility of a subdivision of the family Iriarteaccae into three tribes, a 
synopsis of which is included. Synopses and descriptions are also 
given of the genera and species of the two tribes in which the new 
genera are placed. 
A paper follows (part 7) in which Dr.N. L. Britton and Doctor Rose 
put on record some results of their joint studies in the cactus family, 
describing seven new species and revising several old names. As the 
authors are likely to publish in the Contributions from time to time 
further results of their work in this field, it has seemed advisable to 
connect their reports in a series under a uniform title. 
The succeeding paper (part 8), by Mr. Cook, is in the nature of a 
continuation of a study on the “Relationships of the Ivory Palms,” 
published as volume 13, part 5, of these Contributions. The results 
reached in the former study are applied to the classification of another 
aberrant genus of palms whose affinities have been misunderstood. 
In the way of a conclusion the paper gives the outlines of a general 
treatment of all the American palms. 
Another paper (part 9), by Doctors Britton and Rose, follows, 
dealing with Epiphyllum and related genera of the family Cactaceae, 
the treatment being similar to that of the genus Cereus and its allies 
in volume 12 of the Contributions, but including in addition South 
American species. It is parallel also to the preliminary treatment 
of the tribe Opuntioideae, by the same authors, in the Smithsonian 
Miscellancous Collections, volume 50, part 4. Two new genera and 
five new species are described. 
In part 10 Mr. Safford presents further results of his studies in 
tropical American Annonaceae, dealing with a subgroup of the genus 
Annona, which he distinguishes as a new section, Pilannona, with 
Annona sericea as its type. Ten species are recognized, of which 
seven are described as new. ‘The older species are redescribed after 
a critical examination of the type specimens. . 
In the next number (part 11) Mr. Cook reviews the botanical history 
of two well-known tropical fruit trees, the sapote and the sapodilla. 
The following paper (part 12),on the tribes Hauyeae and Gongylo- 
carpeae of the evening primrose family, by John Donnell Smith and 
Doctor Rose, is of a monographic character, embodying all that is 
at present known of these two tribes. The tribe Gongylocarpeae is 
here first established, as are also two of the genera and one of the 
species. The authors have availed themselves of the resources of 
the National Herbarium, and Doctor Rose has had the additional 
advantage of a field acquaintance with Xylonagra and Burragea in 
