In Chapter 28 of _LOM_ Twain admits to being flattered when he observes a
passing vessel named "Mark Twain":

    "Far along in the day, we saw one steamboat; just one, and no more.  She
was lying  at rest in the shade, within the wooded mouth of the Obion River.
The spy-glass revealed the fact that she was named for me--or _he_ was named
for me, whichever you prefer.  As this was the first time I had ever
encountered this species of honor, it seems excusable to mention it, and at
the same time call the attention of the authorities to the tardiness of my
recognition of it."

Of course, the steamboat may not have been named for him, but for the depth
call from which his own name was fashioned.   Nonetheless, he wants us (and
"the authorities") to take note of it,  perhaps, to reinforce the connection
between his pseudonym and the moment when Bixby has arranged for the
leadsman to call out "Mark twain!" as a signal of pseudodanger.

Larry Howe