Classification of the Ganoids. 337 



characters will leave them no choice. The Lejjtolepides and 

 Megaluri have the true biconcave vertebra3 of the Teleostei ; 

 but there is, nothing astonishing in the fact that there was 

 among the most ancient Teleostei a type (the Caturi) with a 

 more embryonic spinal column — that is to say, with " annular 

 vertebree " or " semi vertebrae. " 



e. If the Acanthodei should be classed with the Ganoids, 

 they will undoubtedly form a separate division ; but I am 

 rather of the opinion of those authors who regard them as a 

 special type among the Chondrostei. The reader will consult 

 with advantage the excellent exposition of this question given 

 by Prof. Huxley in 1861. Lastly, whether we regard this 

 remarkable family as the group of Ganoids most nearly ap- 

 proaching the Selacliia, or as the Selachian type nearest to 

 the Ganoids, is not of much consequence in reality. 



f. Finally, with regard to the Placodermi^ I must in the 

 first place declare that I do not understand why so much stress^ 

 has lately been laij upon the profound diversity of type be- 

 tween the Ceplialaspides on the one hand, and the Coccostei 

 (Avith Pterichthys) on the other. Prof. Huxley regards the 

 latter as true Teleostei, and places the CepJialaspides provi- 

 sionally with the Stm-geons, at the same time indicating their 

 analogy with the Siluro'idei. In my opini(3n, these are all ani- 

 mals of uncertain position, " incertce sedis,''^ the true affinities of 

 which still remain to be discovered. If we are still to persist 

 in regarding them as " cuirassed Ganoids,''^ it will be neces- 

 sary to establish for them a sj)ecial division (fourth or third) 

 in the suborder of Ganoids. 



What J then, is a Ganoid? If it is absolutely necessary to 

 give a definition, it must be formulated nearly as follows : — 

 Every fish (abdominal, malacopterygian, physostome) loith 

 osseous scales, articulated (as in the Lejiidostei) or interlocked 

 (in the manner of the Pycnodonts), oy ivith gular lilates in place 

 of the hranchiostegal rays, and with the p)ai red fins fringed and 

 scaly (as in iho, Poly])teri), or lohich combine several of tliese 

 characters, loill he classed among tlie Ganoids *. And with 

 regard to the position and rank Avhicli the Ganoids should 

 occupy in the system, it will be necessary to form with them 

 a suborder of the Physostome Teleostei, touching upon the 

 Chondi-ostei, but separated from these by the Sturgeons, and 

 surrounded by the Jurassic Teleostei, the Amiidie, and the 



* Even if we should prefer to suppress the suborder Ganoidei alto- 

 gether, and to place the three families Lepidostcidoi, LcpidophuridtCy and 

 Fulypteridce after the Siluri, C/iarcicuii, Ci/prini, tSahnones, and tlie other 

 physostome families, tlie term "Ganoid" must still he regarded as a 

 general denomination for these three families, which arc so intimately 

 connected. 



