caption: The image shows four different types of freshwater mussels on a black background, with the text "mytilopsis adamsi morrison, 1946 holotype usnm 542184" at the top. The mussels are arranged in a line, with each one having a unique shape and texture. The colors of the mussels range from light brown to dark brown, with some having a glossy sheen. The text is written in a bold, white font, making it stand out against the dark background.