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THE AMERICAN NATURALIST. [Vol. XXXVII. 



and Dipnoans, Dr. Hay proposes a new subclass, Azygostei, the 

 Crossopterygians, Ganoids and ordinary fishes forming a third sub- 

 class, Teleostomi. Apparently the relative position of Dipnoans, 

 Crossopterygians, Arthrodira and Aspidoganoids is not yet clear 

 enough to render this arrangement inevitable. The Arthrodira may 

 be allied to the Aspidoganoids ; the Aspidoganoids may be modified 

 sharks, or even modified lampreys. The Crossopterygians may be 

 ancestors of Dipnoans on the one hand and of Ganoids and bony 

 fishes on the other, and there are numerous other elements of uncer- 

 tainty. Under the head of the superorder Placodermi, Dr. Hay 

 removes the Antiarcha (Asterolepis etc.) from the Aspidoganoids, 

 and places them alongside the Arthrodira, which are regarded as a 

 second order of Placoderms. The other superorder of Azygostei is 

 that of Dipnoi. Pterichthyodes is necessarily substituted for the 

 familiar but preoccupied name, Pterichthys ; Phlyctaenaspis is need- 

 lessly substituted for Phlyctaenius, on account of the earlier name 

 Phlyctaenium. Naturalists must sooner or later come to the rule 

 that a name is constituted by its spelling, not by its etymology. 

 Words spelled differently are different words. Puer is a definably 

 different creature from puella, whatever the likeness. 



Under the subclass Teleostomi, we have two superorders, Crossop- 

 terygia and Actinopteri. The name Ganoid disappears, the different 

 types forming three orders, Chondrostei, Pycnodonti and Holostei, 

 at the base of the series of Actinopteri. The name Megalichthys 

 replaces the later Rhizodus, and Parabatrachus is applied to the 

 genus formerly wrongly called Megalichthys. PalEeoniscum is restored 

 as the original spelling of Palaeoniscus, and Lepisosteus as the origi- 

 nal, though unclassic orthography of Lepidosteus. Redfieldius is 

 used for the genus, wrongly called Catopterus, by J. H. Redfield. 



Ginglymodi is restored as the name of the suborder of Gars, and 

 Halecomorphi for the relatives of Amia. The name Eugnathus, pre- 

 occupied, is replaced by Isopholis ; Erisichthe and Pelecopterus are 

 united with Protosphyraena and placed with the Pachycormida; among 

 the Halecomorphi. 



The Nematognathi are separated from the Plectospondyli and 

 placed before the Isospondyli, where apparently they do not belong. 

 The Suckers are reduced to a subfamily of Cyprinidae. A new order, 

 Phthinobranchii, is proposed to include the Hemibranchii and the 

 Lophobranchii, two groups not fundamentally distinct. The Cato- 

 steomi of Boulenger corresponds to this group, except for the inclu- 

 sion of Lampris, a genus of peculiar and primitive structure, but surely 



