Lewis and Clarke, in the Journal of their expedition up the Missouri River, describe the remains of fortifications on Bonhomme Islands at as early a date as 1804–5–6, but until recently their statements have been received with a degree of doubt.[16] This doubt has, however, been fully set at rest by the members of the United States Geological Surveying Expedition of 1872. Not only has it been shown that works exist at Bonhomme’s Island, but all the way up through the Yellowstone region and on the upper tributaries of the Missouri mounds are found in profusion.[17] Dr. C. Thomas, of the above-named expedition, made interesting discoveries in Dakota Territory, near the Northern Pacific Railroad crossing of the James River. Mounds were examined giving evidence of perhaps greater antiquity than those common in the interior of the country, if their contents be depended upon as furnishing a means of test.[18] The Missouri valley seems to have been one of the most populous branches of the wide-spread Mound-builder country. The valleys of its affluents, the Platte and Kansas rivers, also furnish evidence that these streams served as the channels into which flowed a part of the tide of population which either descended or ascended the Missouri. The Mississippi and Ohio river valleys, however, formed the great central arteries of the Mound-builder domain. In Wisconsin we find the northern central limit of their works; occasionally on the western shores of Lake Michigan, but in great numbers in the southern counties of the State, and especially on the lower Wisconsin River. The peculiar and fantastic forms of most of these mounds have led some writers to suppose that they belonged to a different race from that which occupied the valleys to the south. Instead of the usual type of the pyramid and circle, these remains mostly represent animals, or birds, or men. Still Dr. Lapham, who has described them fully in his admirable work[19] on the _Antiquities of Wisconsin_, concluded that sufficient resemblances between these remains and those of the south exist to ascribe to them a common origin. A few instances of the circle and square are found in association with the animal mounds, while in Ohio, on Brush Creek in Adams County, the “Great Serpent,” and the “Alligator” in Licking County furnish proof that either the same people built them or at least the same impulses, religious or otherwise, actuated the people of both districts. The former of the above figures is well described by its name, “with its head conforming to the crest of a hill, and its body winding back for 700 feet in graceful undulations, terminating in a triple coil at the tail.” The length of the latter “from the point of the nose following the curves of the tail to the tip, is about 250 feet, the breadth of the body forty feet and the length of the legs or paws each thirty-six feet.”[20] Until recently no effigy mounds were believed exist further south than Ohio; however, Mr. C. C.