he has since published is his "Description of Vertebrate Remains, chiefly from the Phosphate Beds of South Carolina," in the eighth volume of the journal of the Academy.
Finding that the activity and enthusiasm of the younger naturalists, who had taken up the study of the extinct fauna of the West, were quite sufficient to guarantee the prompt use of the fine collections which still continue to be received from that region, and constitutionally indisposed to take part in the battle for priority, Dr. Leidy availed himself with pleasure of the opportunity to study a group of minute organisms to which he had already given some attention. For the next four years he devoted all his spare time to collecting, studying and delineating the fresh-water rhizopods of America, and the results of his work are embodied in the twelfth volume of the report of the United States Geological Survey of the Territories. The memoir is entitled "Fresh-water Rhizopods of North America," and is perhaps the best illustration of Dr. Leidy's qualities as a naturalist, and the most enduring monument to his industry, which has yet appeared. While preparing the work he spent the greater portion of two seasons in the West, under the auspices of the Survey, and made careful explorations of the country about Fort Bridger, the Uintah Mountains, and the Salt Lake Basin, in search of materials for the memoir.
Since the issue of this superb monograph, Dr. Leidy has been engaged in preparing a new edition of his manual of human anatomy. When this is finished, he intends collecting material for an elaborate illustrated work on parasites. He will probably publish, in the next number of the journal of the Academy, a paper on the parasites of the white ant, many curious forms of which were brought to his notice during his studies of the rhizopods.
The value of Dr. Leidy's scientific work has lately been substantially recognized by the Council of the Boston Society of Natural History, which awarded him the Walker Prize. On account of the extraordinary merit of his researches, the prize, which usually consists of the sum of $500, was on the occasion increased to $1,000.
In the performance of the great scientific work thus imperfectly recorded, Dr. Leidy has confined himself to the duty of accurately describing what he has seen. He very rarely draws inferences from his accumulated facts, and his innate truthfulness is such as to deter him from theorizing. As a lecturer he rarely indulges in figures of speech or flights of fancy. He is deliberate and lucid in his statements, some of his word-pictures being so nearly perfect as to make the fine blackboard drawings with which he often illustrates his remarks almost unnecessary. His delight at acquiring knowledge of a new fact is only equaled by his pleasure in communicating it to others.
