The ornamental design for a mobilestoragetank, as shown and described.
FIG. 1 is a front elevational view of a mobile storage tank showing my new
design;
FIG. 2 is a rear elevational view thereof;
FIG. 3 is a right side elevational view thereof with the tank lids open, a
left side elevational view being substantially the same as the right side
elevational view shown; and,
FIG. 4 is a top plan view thereof with the tank lids closed, the bottom
view being substantially unornamented.