A library in bacteriophage lambda DASH (Stratagene, Inc.) containing Saccharomyces cerevisiae insert DNA was screened with a sea urchin ets probe and four hybridizing clones were isolated. For each of these clones, restriction fragments were identified that contained the hybridizing sequences. In the case of Lambda-JL202, one such fragment consisted of a 4.9 kb HindIII fragment. This fragment was physically mapped by hybridization to a Chromoblot and to a mapping membrane. The hybridization to the Chromoblot demonstrated that the fragment was on chromosome 11. Hybridization was observed at two phages on the mapping membrane. These phage overlap and are derived from chromosome 11.