The family Limnocytheridae is represented in Canada by 22 species belonging to the genus Limnocythere and subgenus Limnocytherina. The following are described as new: Limnocythere (Limnocytherina) paraornata, Limnocythere (Limnocytherina) parascutariense, Limnocythere platyforma. The family Loxoconchidae is represented by the marine-brackish water form Cytheromorpha fuscata.