Further investigation of the Caribbean marine sponge Agelas dispar for biologically active constituents has led to the isolation of the novel bromopyrrole alkaloids longamide B (1), and clathramides C (2) and D (3), whose structures have been determined by spectroscopic methods. Isolation of the known keramadine (4) and of the ecdysonic sterols ecdysterone (5) and ajugasterone C (6) is also reported. The antimicrobial activities of the isolated bromopyrrole alkaloids is summarized.