Narrative of an Expedition Through the Upper Mississippi to Itasca Lake, the Actual Source of This River / Embracing an Exploratory Trip Through the St. Croix and Burntwood (or Broule) Rivers

by Henry Rowe Schoolcraft

19. Unio verrucosus, Barnes, Lea. St. Croix River of the Upper Mississippi.

20. Unio plicatus, Le Sueur, Say. Prairie du Chien, and River St. Croix.

The specimens of U. plicatus sent from this locality by Mr. Schoolcraft have the nacre beautifully tinged with violet, near the posterior border of the shell, and are also much more ventricose them those found in more eastern localities, as Pittsburgh, for example; at the same time, I believe them to be of the same species. Similar variations are observed in other species; the specimens from the south and west generally exhibiting a greater development.

21. Unio trigonus, Lea. From the same locality as the last, and like it unusually ventricose.

22. Unio ebenus, Lea. Upper Mississippi, between Prairie du Chien and Lake Pepin.

23. Unio gibbosus, Barnes. St. Croix River, Upper Mississippi.

24. Unio rectus, Lamarck. U. prælongus, Barnes. Upper Mississippi, from Prairie du Chien to Lake Pepin, and the River St. Croix. The specimens collected by Mr. Schoolcraft, vary much in the color of the nacre. Some have it entirely white, others, rose purple, and others entirely of a very fine dark salmon color. This species inhabits the St. Lawrence as far east as Montreal.

25. Unio siliquoideus, Barnes, and U. inflatus, Barnes. Upper Mississippi, between Prairie du Chien and Lake Pepin. Large, ponderous, and the epidermis finely rayed.

26. Unio complanatus, Lea. U. purpureus, Say. Lake Vaseux, St. Mary’s River. Lake Vaseux is an expansion of the River St. Mary, a tributary of the upper lakes. This shell does not appear to exist in any of the streams flowing into the Mississippi.

27. Unio crassus, Say. Upper Mississippi, Prairie du Chien.