Minnesota is almost unique in that its waters drain by three divergent courses: the Red River to the Arctic, the Great Lakes to the Gulf of St. Lawrence and the Mississippi River to the Gulf of Mexico. The close proximity of the headwaters of these several drainages present opportunities for certain species to move from one basin to another. Species restricted to the Arctic basin have their southern limits in northern and western Minnesota. Many eastern and southern species have their northern and western limits within the state. In spite of the fact that intensive collecting has been carried on since 1890 by various workers new records or range extensions are made each year