Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
inter-sterno, strāvi, strātum, 3, v. a., to strew or lay between or among (perh. only in part. pass.): bitumine interstrato, Just. 1, 2, 7: assulis interstratis, Plin. 29, 2, 9, § 34.
interstrātus, a, um, Part. pass. of intersterno.