From the sponge Ianthella basta collected in Guam, four new bastadin type ethers, bastadin-8 (7), -9 (9), -10 (8), and -11 (10) were isolated together with the known bastadin-2 (4), -4 (3), -5 (5), and-6 (6). Structures were elucidated by extensive spectroscopic analysis and some derivative formation (methyl ethers). 13C NMR assignments for bastadin-4 and -8 were made by one-bond and long-range H/C correlations. Several of the bastadins were found to exhibit cytotoxic and antiinflammatory activity.