1897.] NATURAL SCIENCES OE PHILADELPHIA. 533 



He never described an individual as a specific representative. He 

 insisted that a species could never be represented by one individual, 

 or even by one sex only. The characters of both male and female 

 combined were necessary to make it intelligible, and the true idea 

 of a species comprises also all of its variations in both sexes. Almost 

 as a logical necessity he did not believe in types, and I do not think 

 that there is a single specimen in his entire collection so labelled. 

 In his view every specimen in his hands, when he described a 

 species, was equally a type, and the only concession he would make 

 toward the single example idea was to place one specimen on the 

 label. 



This is a point on which opinions vary. I am not sure that I 

 would like to go quite so far as he in this particular. I believe that 

 the Doctor was perfectly correct in his idea of a species. It seems 

 to me, indeed, the only logical conception ; but I am not certain 

 that it was good policy to neglect the designation of an individual 

 as representing the described combination. No man is infallible, 

 and even Dr. Horn may have confused two species under one name, 

 and the designation of an individual type would possibly save trouble 

 afterward in selecting the particular form which should stand for 

 the name proposed by him. 



Dr. Horn was a hard worker in every sense of the word. His 

 temperament was such that he was never really happy unless at 

 work, and a fair day's scientific labor was always accomplished, 

 even when the demands of his profession kept him up for almost 

 entire nights. It needs only a reference to the publications of the 

 American Entomological Society to get some idea of the amount of 

 work that was accomplished, and as to its quality, the standard 

 remains the same up to the very last paper published by him. 



His work began with Descriptions of three new species of Gor- 

 gonidce in the Collection of the Academy, published in the Proceed- 

 ings for 1860, p. 233, or thirty-seven years ago. 



His first entomological paper : Descriptions of new North Amer- 

 ican Coleoptera in the Cabinet of the Entomological Society of 

 Philadelphia, was published in the same volume, pp. 569-571, with 

 Plate 8. 



The list of his papers comprises 240 titles, only six of them non- 

 entomological, and in them about 150 new genera and more than 

 1.550 new species were characterized. The papers are not widely 

 scattered : the Proceedings of this Academy, of the American Philoso- 



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