GI Dynamics Inc., a Watertown, Mass.-based developer of medical devices to treat obesity, has raised $15 million in additional Series C funding. Return backers include Advanced Technology Ventures, Cutlass Capital, Domain Associates, Johnson & Johnson Development Corp., Polaris Venture Partners and Seedling Enterprises. The company secured a $30 million first tranche back in 2006, while this latest financing closed last December. GI Dynamics has now raised over $60 million in total VC funding since its 2003 inception. www.gidynamics.com