PROFESSOR LOUIS AGASSIZ. 609 



anatomy. He next entered the University of Munich, where, in com- 

 pany with Martius, Oken, Dollinger, and Schelling, he devoted himself 

 eagerly to the pursuit of natural history. At that time Martius was 

 publishing his great work on the "Natural History of Brazil," and, 

 upon the death of Spix, who was editing the zoological portion, Mar- 

 tius intrusted to Agassiz the description of the fishes. In this work, 

 which was admirably well done, Agassiz characterized nine genera, 

 embracing forty-two species new to science. 



For some time Agassiz had contemplated a monograph on the 

 " Fresh-water Fishes of Central Europe," but pecuniary embarrass- 

 ment rendered this impossible, till a bookseller by the name of Cotta, 

 to whom Agassiz showed the material he had collected, furnished 

 him the means necessary for its completion. Meanwhile he studied 

 and obtained the degree of Doctor of Medicine at Munich, and of 

 Doctor of Philosophy at Erlangen. After his examination, Agassiz 

 went to Vienna, and applied himself closely to the study of actual 

 and fossil ichthyology. From Vienna he went to Paris, where he 

 made the acquaintance of Cuvier and Humboldt, both of whom 

 warmly welcomed this expert young naturalist. Here he lived on 

 the most intimate terms with Cuvier till the death of that naturalist, 

 in 1832, when he returned to Switzerland and established himself at 

 Neufchatel, where he was appointed Professor of Natural History, a 

 position he held till his departure for America. 



Through the influence of Humboldt, between whom and Agassiz 

 there existed the warmest friendship, he was enabled to begin the pub- 

 lication of his " Poissons Fossiles," a work evincing such careful and 

 profound research, and such a wonderful power of generalization, as to 

 obtain for him a place among the very first naturalists of the day. 

 This work, which appeared in parts, between the years 1833 and 1845, 

 comprises five volumes, of about 1,700 quarto pages, with an atlas of 

 400 folio plates, and contains descriptions of nearly a thousand species 

 of fossil fishes. Aside from the great number of species, genera, and 

 families established, Agassiz adopted an entirely new system of classi- 

 fication. In the classification proposed by Cuvier, fishes were divided 

 into two orders, according to the nature of the skeleton, viz., cartilagi- 

 nous and osseous. Agassiz — looking upon the external covering of the 

 animal as a reflex of the connection existing between the being and 

 its surroundings, bearing the imprint of all the peculiarities of its ex- 

 istence, and consequently of its organization — deemed that the true 

 principle of the classification of fishes was to be found in the scales. 

 In view of this he proposed a division of the families of fishes into four 

 orders, viz., JPlacoids, in which the scales are represented by plates of 

 enamel, as in the sharks ; Ganoids, in which the scales consist of an- 

 gular bony plates covered with a thick layer of enamel, as in the gar- 

 pikes ; Gtenoids, or fishes with true scales, in which the posterior edges 

 of the laminae are toothed ; and Cycloids, in which the scales are com- 



VOL. IV. — 39 



