Long Fingernailclam (Musculium transversum) is a medium-sized (shell length up to 1.2 cm) freshwater peaclam that is distributed throughout North America east of the Rocky Mountains, excepting most northern Atlantic provinces and states. In New Mexico it occurs in San Miguel and Union Counties. They are found burrowed on the bottom of sloughs, rivers, and large lakes in perennial, usually running, water. They reproduce by hatching within the adult and then the young are expelled as juvenile clams.