2. Tables have been moved to avoid splitting paragraphs. In some
cases the tables have been reconfigured or split in order to work
better with e-readers.
3. Except as mentioned above every effort has been made to replicate
this text as faithfully as possible, including non-standard
punctuation, inconsistently hyphenated words, etc.
4. The original printed text is available from HathiTrust at:
https://hdl.handle.net/2027/uc1.b3805680 (see pg 353). The outline
“CLASSIFICATION OF NEBULAE” starting on page 3 lists N.G.C. 2117
as a type E7 nebula. The version of this paper printed in
_Contributions from the Mount Wilson Observatory_ No. 324 lists
N.G.C 3115. Otherwise the papers are essentially identical.
Special notation for the plain text version: