Lieutenant James William Abert (1820-97) of the United States Army Topographical Engineers received orders in 1845 to explore the Canadian River region of the southern plains--an area covering present-day Colorado, New Mexico, Texas, and Oklahoma. Although this land was still in Mexican territory, the United States had gradually abandoned most of the diplomatic niceties regarding its boundaries with Mexico by that time.   Abert set out from Bent's Fort to conduct a detailed reconnaissance. He possessed a great eye for detail, providing in his journal graphic descriptions of the birds, plants, and animals he encountered as well as clear depictions of the countryside. Moreover, Abert observed in great detail the Kiowas and Comanches who often approached his expedition to see if he and his men were the much hated 'Texans' with whom they were at war. His firsthand account of the Kiowas and Comanches contains valuable information not previously available.   The 1804 Lewis and Clark Expedition marked the beginning of Anglo-American exploration of the American West. Abert's account of his four-month journey by mule train is invaluable as one of the concluding records of that period.