joined together the slider is slidably mounted on the lower casing member so as to cover at least a part of a bottom and a side of the lower casing member the upper casing member is provided at a rear portion of both sides thereof with holding members through which the casing is grasped the holding members are separated or isolated from the slider to assure smooth sliding movement of the slider the casing body may be provided on both sides thereof with reliefs which serve to prevent the holding members from interfering with movement of the slider application_number US 5883987 A description a casing for a magnetic tape cassette according to the present invention will be described below with reference to fig3 8 fig3 and 4 illustrate an embodiment of a casing for a magnetic tape cassette according to the present invention which is generally designated by reference numeral 10 in the illustrated embodiment and which includes a casing body 12 comprising an upper casing member 14 and a lower casing member 16 integrally joined together by means of screws to define a space therewithin the terms 34 upper 34 and 34 lower 34 as used herein are merely relative to one another in other words the casing 10 illustrated in fig3 may be conveniently inverted so that the upper casing member 14 becomes the 34 lower 34 member while the lower member 16 thereby becomes the 34 upper 34 member in the so formed casing body 12.