JOSEPH LEIDV. 439 



winter of 1852 Professor Horner through ill health was unable to con- 

 tinue his lectures on anatomy, and at his request Dr. Leidy was ap- 

 pointed as his substitute. After the death of Dr. Horner, he was, in 

 May, 1858, appointed Professor of Anatomy, which position he held 

 until his death. 



During the ten years preceding his appointment to the Chair of 

 Anatomy, in addition to his regular duties, Dr. Leidy found time to 

 continue his scientific studies. In 1844, the year of his graduation, he 

 contributed to Amos Binney's monograph of the Mollusca an admira- 

 ble introductory chapter on the " Special Anatomy of the Terrestrial 

 Mollusks of the United States," together with sixteen beautifully 

 executed plates illustrating the anatomy of thirty-eight species of Mol- 

 lusca. In 1 845 he was elected a member of the Boston Society of Nat- 

 ural History, and of the Philadelphia Academy of Natural Sciences. 

 With the latter institution he was constantly associated during the rest 

 of his life, being successively Librarian, a Curator, and from 1847 

 chairman of the Board of Curators. With his natural mpdesty, he 

 many times refused the office of President, but finally in 1881 accepted 

 it, and remained President of the Academy to the end of his life. 



The Proceedings of the Academy furnish a brilliant memorial of his 

 great attainments in various branches of natural science, as they con- 

 tain several hundred valuable contributions to zoology, paleontology, 

 comparative, human, and microscopic anatomy, botany, and mineralogy. 

 While he never regarded liimself as an authority, and published but 

 little upon mineralogy and botany, his knowledge of these subjects was 

 that of a specialist. This was well shown by the frequent verbal com- 

 munications which he made as Curator in calling the attention of the 

 Academy to additions to the mineralogical cabinet ; his knowledge of 

 gems and their values was also very extensive. The very fine and 

 valuable mineralogical collection made by him has recently been pur- 

 chased by the government, and will be placed in the National Museum 

 in Washington. 



His familiarity with plants was also frequently noted at the meet- 

 ings of the Academy and elsewhere. The herbarium which he gave 

 the Biological Department of the University of Pennsylvania contains 

 over 1,500 species which were collected and determined by himself. 



In zoology he gave especial attention to invertebrate forms ; and 

 while paying particular attention to parasites and Protozoa, he made 

 valuable contributions to our knowledge of many other groups. As 

 early as 1846 he observed minute specks in some pork that had been 

 cooked, which, when examined with a microscope, were found to be a 



