  The interacting binary system NGC 4490/85 = Arp 269 is intermediate in mass
between the Milky Way/Large Magellanic Cloud and the Large/Small Magellanic
Cloud binary systems. It is a system of 14 known galaxies. We estimate the
total Newtonian gravitating mass of the NGC\,4490/85 group to be M_T = (1.37 +-
0.43) times 10^{12} M_Sun using radial velocities and projected separations of
its 13~candidate members. The system of dwarf satellites in the group
demonstrates signs of coherent rotation in the same direction as that of the
extended HI-shell surrounding the central interacting galaxy pair. The origin
of this phase-space correlated population of star-forming late-type satellite
galaxies raises questions in view of the planes-of-satellites observed around
more massive galaxy pairs that are, however, made up of old early-type dwarf
galaxies. We also report the detection of a candidate stellar Plume near the
binary. This elongated structure of low surface brightness is a likely optical
counterpart to the HI-tail north of NGC 4490/85, recently discovered by the
FAST radio telescope.
