Lewis & Short

inter-lābor, lapsus sum, 3, v. dep. n. and a., to fall, slip, slide, glide, or flow between (poet.): per has stellis interlabentibus umbras, Stat. Th. 2, 649: (in tmesi), inter enim labentur aquae, Verg. G. 2, 349; Sil. 6, 18.
With acc.: fluvius lucos, Amm. 22, 8, 17.