#kindle supports .txt but not #epub

cyb/kindle formats don't include epub:
6.11: summary:
. I'm interested in amazon's Kindle; because,
it has the largest E Ink display on the market;
and, unlike the Nook, it also shows .txt files,
which most of my docs are already formatted as;
however I was needing html access too;
and epub support would have been convenient
since Nook already has me converting to that;
but, Amazon also has an email conversion service
if you don't mind your content being In The Cloud
(available to not only NSA but also many other authorities).
. if you are not confined to Chrome OS,
there are local apps for converting epub to mobi .

1.13: web:
 amazon.com`Kindle-DX (latest model):

 9.7" diagonal E Ink Pearl  display;
1200 x 824 pixel resolution at 150 ppi,
16-level gray scale, 10:1 contrast ratio.
Size (in inches): 10.4" x 7.2" x 0.38".
Content Formats Supported: # natively:
Kindle (AZW), PDF, TXT,
Audible (formats 4, Audible Enhanced (AAX)),
MP3, unprotected MOBI, PRC;
# through conversion:
HTML, DOC, RTF, JPEG, GIF, PNG, BMP

Kindle does not support EPUB:

. EPUB is the most widely supported  format that is
vendor-independent XML-based (as opposed to PDF);
that is, it is supported by the largest number of e-Readers.
The popularity of Amazon.com's Kindle devices in America
has led also to the prominence of KF8 and AZW formats;
. Kindle KF8 Format (.azw; .kf8):
in late 2011, Amazon.com released Kindle Format 8;
The .kf8 file format supports
a subset of HTML5 and CSS3 features,
with some additional nonstandard features;
the new data is stored within a container
which can also be used to store a MOBI content document
(allowing limited backwards compatibility).
. Older Kindle eBook readers use the
proprietary format, AZW.
It is based on the Mobipocket standard,
with a slightly different serial number scheme
(it uses an asterisk instead of a dollar sign)
and its own DRM formatting.
The Kindle AZW format also lacks some Mobipocket features
such as JavaScript.
Amazon has developed an .epub to .mobi converter
called KindleGen (supports IDPF 1.0 and IDPF 2.0 epub format,

Mobipocket Format (.prc; .mobi) not on Android:

The Mobipocket e-book format is based on
the Open eBook standard using XHTML
and can include JavaScript and frames.
It also supports native SQL queries for embedded databases.
Readers can add blank pages in any part of a book
and add free-hand drawings. Annotations
 — highlights, bookmarks, corrections, notes, and drawings —
can be applied, organized, and recalled from a single location.
Images are converted to GIF format
and have a maximum size of 64K,
sufficient for mobile phones with small screens,
but rather restrictive for newer gadgets.
Mobipocket Reader has electronic bookmarks,
and a built-in dictionary.
The reader has a full screen mode for reading
and support for many PDAs, Communicators, and Smartphones.
Mobipocket products support most
Windows, Symbian, BlackBerry and Palm operating systems,
but not the Android platform.
Using WINE, the reader works under Linux or Mac OS X.
Third-party applications like
Okular and FBReader
can also be used under Linux or Mac OS X,
but they work only with unencrypted files.
. Long term plans for the Mobipocket platform
are in question in the wake of Amazon's announcement of
the Kindle Format 8,
which moves in the direction of HTML5 and CSS3.
As one of the most popular e-reader devices,
the Kindle has great sway in the popularity of e-reader formats.

-- calibre on most platforms can convert .mobi
to whatever you wish to edit in:
epub( with sigil), rtf ( with MS word)...
then convert back to mobi.