584 ANNUAL EEPORT SMITHSONIAN INSTITUTION, . 1916. 



His revisions naturally met with criticism from those long familiar 

 with the existing order. In a majority of cases he lived to see his 

 views accepted by authorities on fishes. His ideas on Avian classifi- 

 cation are quite different from those generally accepted, especially 

 in regard to the relative taxonomic value of characters, but it is by 

 no means certain that the views of future ornithologists will not 

 much more closely approximate to those of Gill. 



His work on mollusca, excepting the general classification em- 

 bodied in the " Arrangement of the families of mollusks," was chiefly 

 of the nature of revisions of particular families or genera. The 

 " Arrangement of families " brought together the most complete 

 knowledge existing at the time of the relations of the different groups 

 of mollusks; but the subsequent advance of science in that respect 

 has been relatively much greater than in mammals or fishes, and 

 Gill's arrangement has at present chiefly an historical value. 



Of the arrangement of the families of fishes and mammals others 

 can speak with an authority denied to the present writer, but the 

 impression left after conversation with experts is confirmatory of 

 their exceptional value. 



The present Commissioner of Fisheries has had the kindness to 

 furnish for this memoir the following estimate of Dr. Gill's work on 

 fishes: 



Dr. Gill's chief contributions to ichthyology were his taxonomic papers. In 

 his taxonomy, which was largely supported by his osteological research, he had 

 no equal among his contemporaries in America or abroad. His papers represent 

 a very large amount of painstaking investigation of a character for which he 

 was especially well fitted and for which few active workers have the time, the 

 fitness, or the inclination. His conclusions have been very generally accepted 

 and form the basis for our present classification of fishes. While for years 

 European ichthyologists disagreed with his views, his system has finally been 

 accepted by practically all the active men at the present time. Next to his 

 taxonomic contributions rank his papers on the structure and habits of fishes. 

 His papers on the life histories of fishes also are noteworthy, their chief value 

 being in the assembling and weighing of scattered observations and their pres- 

 entation in form that is exceedingly helpful to all workers in this field. 



His knowledge of the biological literature of all countries and all times was 

 amazing and profound. In estimating his influence on science, full cognizance 

 should be given to the readiness with which he placed this knowledge, together 

 with his time and talents, at the disposal of everyone, and to the permanent 

 value of the encouragement he was ever most anxious to give to all those who 

 were fortunate enough to be brought in contact with him. 



In noticing the death of Prof. Gill in the Annual Report of the 

 U. S. National Museum for the year ending June 30, 1915, Mr. 

 Richard Rathbun, Assistant Secretary in charge of the Museiun, thus 

 expresses himself in regard to his colleague and collaborator : 



Rarely does one find, as in the present instance, the more or less accidental 

 early phases in the groping fbr a career converge in such a manner as to at 



