(written from a Production point of view)
Snodgrass was an individual mentioned on an unused okudagram from the Star Trek: The Next Generation episode "Up The Long Ladder", which was reproduced in Star Trek: The Next Generation - The Continuing Mission.
According to the graphic, First Officer Snodgrass served as First officer under Captain Walter Granger on the SS Mariposa, during its 2123 colonization mission to the Ficus sector. Peculiarly, of the three senior crew members listed, Snodgrass was the only one for which no first name was given.
She or he was most likely named after Melinda M. Snodgrass, who was referenced on another okudagram which did make it on screen as Captain Melinda Snodgrass. This mirrors the other individual mentioned on the unused graphic, Winrich Kolbe, who was also referenced as a captain on the other okudagram.