126 Reviews — Fossil Fishes in British Museum. 



that they differ principally in the dentition and in the condition of 

 the jaws! ' It is to be hoped that Mr. Smith Woodward's emphatic 

 declaration that the " Platysomidaa never make the faintest approach 

 to the Pycnodontidae in a single essential character," as well as the 

 systematic position to which in the present work he has assigned the 

 last-named family, will lead the distinguished palaeontologist of 

 Munich to reconsider a position which still retains us in the Agassiz- 

 Egertonian period of pala?ichthyological science. 



JEtheospondyli. 



We have already seen that Mr. Woodward excludes Lepidostens 

 from the assemblage of semi-heterocercal rhombic-scaled fossil forms, 

 with which it has been associated since the publication of Huxley's 

 famous Essay on the Classification of the Devonian Fishes; and his 

 reason is the structure of the vertebra?, which never, even in the 

 caudal region, show separate and alternating pleurocentra and hypo- 

 centra. This character is shared also by Aspidorlujnchus, though the 

 vertebral centra are here ring-shaped or biconcave, instead of opis- 

 thoccelous as in Lepidosteus. The suborder of iEtheospondyli 

 therefore includes the two families of Aspidorhynchidae and Lepi- 

 dosteidas. 



These two families are certainly closely related to the fishes 

 brought together by Mr. Woodward under Protospondyli, by the 

 complexity of the mandible and other characters, and it may indeed 

 be a matter of opinion as to whether the condition of the vertebras 

 justifies their separation. The author himself states that "the 

 recognition of this group is a confession of ignorance " — that is, 

 ignorance of the immediate relationships of the two families therein 

 included. 



Isospondyli. 



The third group after Chondrostei, which Mr. Woodward com- 

 mences in this Part, is that of the -Isospondyli, a term instituted 

 by Professor Cope for a large and closely i-elated series of recent 

 "Teleostei," including the Clupeoids, Salmonoids, etc., and in which 

 he also placed many of the Mesozoic " Ganoids." dealt with by our 

 author in the previous pages of this volume. The Isospondyli are, 

 however, distinguished from the Protospondyli and iEtlieospondyli 

 by the more simply constituted mandible, which, as in modern bony 

 fishes generally, does not consist of more than two or three pieces, 

 except perhaps in Arapacina. Only three families of Isospondyli 

 are treated of in the present Part, namely, the Pholidophorida?, 

 Oligopleuridas, and Leptolepida?. 



With the inclusion, already proposed by Cope, of fishes like 

 JPholidophorus in one "suborder" with Clupea and Salmo, the 

 " Ganoidei " of Agassiz may be said to have disappeared, and with 

 them the " Palaeichthyes " of Gunther. Strange it is that after 

 having been led so long an excursion by the illustrious founder of 

 fossil ichthyology, our Ganoids should have got back pretty much 

 to where they were — close to the Herrings ! 



1 " Grundzuge der Palteontologie," Miiuchen and Leipzig, 189n, p. 574. 



