Ixvi THE ANIMAL KINGDOM. 



Theory of Natiu'.il Selection, while II. W. Bates, after spending eight years of re- 

 search and travel in Brazil, was also led to adojit the theory of natural selection. 

 Fiitz Miiller (Fiir Darwin, dated Desterro, Brazil, 18G3) and his brother, the late Her- 

 mann Miiller, in numerous botanico-entomological tracts and works, as well as Haeckel 

 in his History of Creation, his Anthropogeny, and other works, and Weissmanu's 

 Studies in the Theory of Descent (1875) are the epoch-making works of this period, 

 based, as they are, on special studies. Expounders of the doctrines were Huxley 

 (1859), Herl)ert Spencer, Haeckel, Asa Gray, and many others. Of the rise of a 

 modernized Lauiarckian school in the United States, of which Hyatt, Cope, Dall, 

 Ryder, and Packard are the supporters, mention has already been made. In Germany 

 this school is represented especially by Semper. 



With a knowledge of zoological classification and embryology, naturalists have, 

 since the jniblication of Darwin's epoch-making work on the origin of species, published 

 theories as to the j)robable ancestry and succession of forms, and entered into the con- 

 struction of genealogical trees, or, in a word, of phylogenies. Haeckel in 1870 first dared 

 to exjiress diagrammatically his views as to the phylogeny of animals in general, his 

 most authoritative work relating to the ccelenterates, especially the medusae. Attempts 

 to trace the genealogy of the insects have been made by Brauei', Packard, Lubbock, 

 and Mayer; Hyatt has elaborated the phylogeny of the Ammonites, and Owen, Hux- 

 ley, Kowalevsky, and Marsh the ancestry of certain ungulates, especially of the 

 horse family, while the phylogenies of the Camelidje, the Carnivora, the Ungulata in 

 general, and other orders, have been worked out by Co]ie. 



The effect of these studies on paleontology has been marked, and have given a new 

 direction to the study of the geological succession of animals. The great works of 

 James Hall, of Barrande, of the Surveys of India, and the ex])lorations in the western 

 tertiaries by Hayden, which were published by Meek, Leidy, and others, and the j^er- 

 sonal explorations of Marsh and of Cope, as well as those of Gaudry in Europe, have re- 

 vealed numbers of forms connecting the orders of living reptiles, birds, and mammals, 

 while the researches on the succession and ancestry of the Ammonites by Hyatt 

 have ojsened new fields of research. 



In 1864 the Norwegian naturalist, M. Sars, and his son, G. O. Sars, carried on 

 dredging to the depth of over 300 fathoms, showing that Forbes (before that time the 

 most prominent writer on marine zoology and the laws of bathymcti'ical distribution), 

 was incorrect in inferring that the sea below the depth mentioned was bai-ren of life. 

 As early as 1850, Michael Sars opposed Forbes' hypothesis, and in 18G4 published a list 

 of 92 different sjjccies discovered at 200-300 fathoms on the coast of Norway, and in 

 1868 he increased the list to 427 species. As the results of his father's and his own 

 examinations. Prof. G. O. Sars, as early as 1869, said : " The results of these, my deep- 

 sea researches, was, however, great and interesting quite beyond all anticipation. . . . 

 And so far was I from observing any sign of diminished intensity in this animal life at 

 increased depths, that it seemed, on the contrary, to me as if there -VN-as just beginning 

 to appear a rich and in many respects a peculiar deep-sea fauna, of ^\iiich only a 

 very incomplete notion had previously existed." The United States Coast Survey, 

 since 1867, under the inspiration and labors of Agassiz and Pourtales, showed that 

 the bottom of the Floridan channel, below 800-500 fathoms, was packed with life- 

 forms ; the Swedish S]ntzbergen expeditions also brought u]j deep-sea animals from 

 2000-3000 fathoms. Meanwhile, the English government sent out the ' Porcupine' and 

 other vessels, the naturalists of which were Carpenter and Jeffreys, who carried on 



