NOTICES BIOGRAPHIQUES. — JOSEPH LEIDY 273 



of his writings lists over 550 separate articles, covering ail depart- 

 ments of natural history. While lie was neither a mineralogist nor 

 a botanist, he made fréquent contributions by the way of short 

 articles in both fields. His collection of gems is preserved in the 

 National Muséum at Washington, and his herbarium constitutes 

 one of the important possessions of the University of Pennsylvania. 

 His work on human and vertébrale comparative anatomy won him 

 deserved prominence in thèse fields. He was one of the first to 

 study the fossil remains from the Bad Lands of Nebraska and the 

 west, and the séries of paleontological researches, extending over 

 a period of forty years, are said by one author to culminate « in 

 discoveries which, together with others made in the same field are 

 regarded by many as going further to estabiish the doctrine of 

 évolution than ail the other facts hitherto advanced in favor of that 

 theory ». His accuracy hère is noteworthy in view of the limited 

 material at hand for comparison and but a small number of errors 

 has been found in his work. 



His contributions to comparative anatomy among invertebrate 

 groups are no less important ; both among Insects and Mollusks 

 he contributed investigations which form the basis of our présent 

 knowledge of thèse groups. It was, however, among the lower 

 forms that his work was particularly noteworthy. Hère he entered 

 upon fields comparatively unbroken and achieved results of the 

 highest permanent value. His work on Protozoa is well shown in a 

 magnificent monograph (1) whose artistic and accurate figures were 

 ail the work of his own pencil. AU his observations were made with 

 wonderful précision in view of the simple instruments at his com- 

 mand. Thus, for instance, he noted in 1861 that the Gregarinida 

 are provided with muscle fibers, a view which was denied by 

 European observers until tliirty years later it was confirmed by 

 the younger Van Beneden. 



In some respects his most striking work was done in the field 

 of helminthology. Among his very first papers was one in 1846 on 

 an entozoan from the Pig in which he announced that he had disco- 

 vered a minute encysted Worm which he regarded as Trichina 

 spiralis heretofore considered as peculiar to the human species. 



(1) Fresh Water Rhizopods of North America. Report of the U. S. Geol. 

 Sarvey of Territories, XII, ix-32t p., 48 pi., 1879. 



Archives de Parasitologie, III, n" 2, 1900. 18 



