Boatmen's Bancshares Inc. reported third-quarter earnings increased 14 percent to $153 million, or 96 cents a common share before the impact of merger-related expenses and the one-time assessment to recapitalize the Savings Association Savings Fund.

Including these non-operation expenses, net income for the third quarter was $125 million, or 79 cents a common share. These totals compare to $134 million or 84 cents a share during the same period of 1995.

Nine-month earnings rose 14 percent, to $439 million, or $2.76 per common share, from $385 million, or $2.42 for the same period a year ago, before the impact of nonoperating items for both years. Including the nonoperating items, net income for the nine months for 1996 rose 9 percent, to $383 million or $2.40 per common share, up from $352 million, or $2.21 per common share in 1995.

Boatmen's Bancshares, with assets of $41 billion, is the largest bank based in Missouri, and is one of the top 25 U.S. bank holding companies. Boatmen's operates at more than 600 sites in nine states.