August 15, 1902.] 



SCIENCE. 



251 



tions which later writers have not altered 

 or removed. Especially important is his 

 classical work, 'Ueber den Bau und die 

 Grenzen der Ganoiden. ' In this he showed 

 the real fundamental characters of that 

 group of archaic fishes, and took from it 

 the most heterogeneous of the elements left 

 in it by Agassiz. To Miiller we also owe 

 the first proper definition of the Lepto- 

 eardii and the Cyclostomi, and, in associa- 

 tion with Dr. J. Henle, Miiller has given 

 us one of the best general accounts of the 

 sharks (' Systematische Beschriebungen der 

 Plagiostomen ' ) . To Miiller we owe an ac- 

 cession of knowledge in regard to the duct 

 of the air-bladder, and the groups called 

 Dipneusti (Dipnoi), Pharyngognathi and 

 Anacanthini were first defined by him, al- 

 though now usually restricted within nar- 

 rower limits than those assigned by him. 



In his work on the Devonian fishes, the 

 great British comparative anatomist, 

 Thomas Henry Huxley, first distinguished 

 the group of Crossopterygians, and sepa- 

 rated it from the Ganoids and Dipnoans. 



Theodore Nicholas Gill is the keenest in- 

 terpreter of taxonomic facts yet known in 

 the history of ichthyology. He is the au- 

 thor of an immense number of papers, the 

 first bearing date of 1858, touching almost 

 every group and almost every phase of re- 

 lation among fishes. His numerous sugges- 

 tions as to classification have been usually 

 accepted in time by other authors, and no 

 one has had a clearer perception than he 

 of the necessity of orderly methods in 

 nomenclature. Among the orders first de- 

 fined by Gill are the Eventognathi, the 

 Haplomi, the Xenomi and the group called 

 Teleocephali, which included all the bony 

 fishes except those which showed peculiar 

 eccentricities or modifications. Dr. Gill's 

 greatest excellence has been shown as a 

 scientific critic. Incisive, candid and 

 friendly, there is scarcely a scientific man 

 in America who is not directly indebted to 



him for critical aid of the highest impor- 

 tance. The present writer cannot too 

 strongly express his own obligations to this 

 great teacher, his master in fish taxonomy, 

 as Agassiz was in fish ecology. Dr. Gill's 

 work is not centered in any single great 

 treatise, but is diffused through a very 

 large number of brief papers and cata- 

 logues, those from 1861 to 1865 mostly pub- 

 lished by the Academy of Natural Sciences 

 in Philadelphia, those of recent date by 

 the United States National Museum. For 

 many years Dr. Gill has been identified 

 with the work of the Smithsonian Institu- 

 tion at Washington. 



Closely associated with Dr. Gill was Dr. 

 Edward Drinker Cope, of Philadelphia, a 

 tireless worker in almost every field of 

 zoology, and a large contributor to the 

 broader fields of ichthyological taxonomy 

 as well as to various branches of descriptive 

 zoology. Cope was one of the first to in- 

 sist on the close relation of the true ganoids 

 with the teleost fishes, the nearest related 

 group of which he defined as Isospondyli. 

 In breadth of vision and keenness of in- 

 sight. Cope ranked with the first of tax- 

 onomic writers. Always bold and original, 

 he was not at all times accurate in details, 

 and to the final result in classification his 

 contribution has been less than that of Dr. 

 Gill. Professor Cope also wrote largely on 

 American fresh-water fishes, a large per- 

 centage of the Cyprinidffi and Percidee of 

 the eastern United States having been dis- 

 covered by him, as well as much of the 

 Rocky Mountain fauna. In later years his 

 attention was absorbed by the fossil forms, 

 and most of the species of the Cretaceous 

 rocks and the Eocene shales of Wyoming 

 were made known through his ceaseless 

 activity. 



The enumeration of other workers in the 

 great field of ichthyology must assume 

 something of the form of a catalogue. Part 

 of the impulse received from the great 



