Statistics for occurrence #1 of “R. M. Clark” in page 244 of Admiral David D. Porter, The Naval History of the Civil War.:
... Mate, G. W. Lane.
Acting-Master's Mate, John Bath. Acting-Master's Mate, Anthony Loper.
Acting-Master's Mate, J. W. Cortelyou. Acting-Master's Mate, Thomas Levindsell.
Acting-Master's Mate, R. M. Clark . Acting-Master's Mate, Thomas McEllmell.
...