on the extinct vertebrates of North America. His first paper on pale- 
ontology was published in 1846, and his last in 1888, as the subject 
occupied him for more than forty years. He laid, with the hand of a 
master, the foundation for the palzeontology of the reptiles and mammals 
of North America, and we know what a wonderful and instructive and 
world-renowned superstructure his successors have reared upon his 
foundation. It was this work that established his fame and brought 
his honors and rewards. ‘They who hold it to be his best title to be 
enrolled among the pioneers of science in America are in the right, in so 
far as the founder of a great department of knowledge is most deserving 
of commemoration; but I do not believe it was his most characteristic 
work. 
I can mention but one of the results of his study of American fossils. 
He showed, in 1846, that this continent was the ancestral home of the 
horse, and he sketched, soon after, the outline of the story of its evolution 
which later workers have made so familiar. 
More than half his papers are on a subject which seems to me to 
contain the lesson of his life. Like Gilbert White, he was a home 
naturalist, devoted to the study of the natural objects that he found 
within walking distance of his home, but he penetrated far deeper into 
the secrets of the living world about him than White did, finding new 
wonders in the simplest living being. In the intestine of the cock-roach, 
and in that of the white ant, he found wonderful forests of microscopic 
plants that were new to science, inhabited by minute animals of many 
new and strange forms. His beautifully illustrated memoir on A 
Flora and Fauna Within Living Animals is one of the most remarkable 
works in the whole field of biological literature. Another memoir 
gives the results of his study of the anatomy of snails and slugs. ‘The 
inhabitants of the streams and ponds in the vicinity of his home fur- 
nished an unfailing supply of material for research and discovery, and 
many of his publications are on aquatic animals. He finally became 
so much interested in the fresh-water rhizopods that he abandoned all 
other scientific work in order to devote his attention exclusively to these 
animals. His results were published in the memoir on The Fresh- 
water Rhizopods of North America. 'This is the most widely known 
of his works. It is, and must long be, the standard and the classic 
upon its subject. I have no time to dwell upon his work as the naturalist 
of the home — his best and most characteristic work. Its lesson to 
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