the present invention relates to a bag for packaging a biological substance , such as animal semen , which is formed by two plastic walls assembled so as to define a pouch for receiving said substance and that comprises a line communicating with said pouch a line for filling the same , this bag comprising in addition at least one pair of openings located on both sides of said line , in order to get hung , via these openings , to fingers that are complementary to a supporting device . this bag is characterized in that at least one of these openings has an oblong shape , extends perpendicularly to said line , and comprises an area forming a hard spot . the invention relates also to a strip formed by juxtaposing such bags , and an assembly comprised of a bag and a hanging support .