II 
In organizing Dr. Cheever's collection it was decided that the slides 
be divided into four groups, sections A, B, C and D. Into Section A were 
placed all those slides which bore determinations. Into Section B was 
placed all those slides which were undetermined, but which bore collection 
localities. Also included in Section B was a number of slides, which turned 
up after the major reorganization had taken place and which are treated in 
the adenda. Section C was catch all for those slides which were not iden¬ 
tified and which bore no collection localities. Section D was set up to 
contain the following three diatom exsiccati: Diatomacearum species typicae 
(no. 1-700); Cleve and Moller's Diatoms (no. 1-300); and Synopsis Des 
Diatomees de Belgique (no. 1-550). 
Section A Boxes A-l to A-41 
Determined slides are indexed alphabetically according to genus and 
then according to species. The actual location of the slides are given by 
letter number combinations located on the extreme right handside of the page 
following each species entry. For example the letter number combination of 
Alloineis antillarum is A-3: 24. The letter number sequence A-3 indicates 
box 3 of Section A. The number "24" following the colon in that sequence 
indicates the slot number. 
During the organization of the collection, all slides which listed 
more than one species were without exception inserted in the collection 
under the first name listed on the slide. All the species were then listed 
in the index giving the same letter-number combination. Thus a given slide 
may be found listed under more than one diatom species and likewise the 
letter-number combinations given after a species may on occasion appear to 
be out of sequence. 
Section B Boxes B-l to B-41 
A-11undetermined slides bearing collection localities are divided 
into two groups. Those collections made in the United States are in 
Group I and are arranged alphabetically by state. Those collections made 
outside the US are in the Group II World division. The slides in the Group 
II are divided into geographic areas and arranged alphabetically by country 
or locality within each area. 
The locations of the slides in Section B are as Section A given in 
the index by the letter-number combinations following each entry. 
Section C Boxes C-l to C-5 
The slides in this section are probably of culturing experiments. 
They are undetermined and bear no collection data; they are therefore 
not indexed. 
Section D Boxes D-l to D-18 
Diatomacearum species typicae D-l to D-7 
Cleve and Moller's Diatoms D-8 to D-10 
Cleve and Moller's Diatoms Incomplete set D-ll to D-12 
Synopsis Des Diatomees de Belgique D-13 to D-18 
