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MR. T. W. BRIDGE ON THE OSTEOLOGY OF POLYODON FOLIUM, 
Giebel,* * * § iii Lis classification of fossil Fishes, retained H. Muller’s subdivisions of 
Holostei and Chondrostei, the genera Polyodon and Acipenser being relegated to the 
last-mentioned group. 
VoGT,f in a system of classification of recent and extinct Ganoids, divided the order 
into the three suborders of (I.) Loricata, which contained the families Cephal- 
aspida, Acipenserida, and Spatularida ; (II.) Rhombifera, including Lepidosteidse, 
Polypteridse, and the extinct Ganoids with rhomboidal scales ; (IIP) Cyclifera, com- 
prising the Amiadie and the cycliferous fossil genera. 
Huxley^ in his essay on ‘ The Systematic Arrangement of the Fishes of the 
Devonian Epoch,’ and subsequently in his ‘Anatomy of Vertebrate Animals,’ arranged 
the recent and fossil members of this order in the following suborders : — 
I. Amiadse. 
II. Lepidosteidse. 
III. Crossopterygidse. 
IV. Chondrosteidae. 
V. Cephalaspidse. 
VI. Placodermi. 
VII. Acanthodidse. 
Lutken,§ declining to separate the Ganoids from the Teleostei, regarded the former 
simply as a subdivision of the Physostomi, thus : — ■ 
Subclass I. Teleostei. 
Order I. Air-duct absent ( Physoclysti ). 
,, II. Air-duct present ( Physostomi ). 
Suborder I. Containing Muller’s families of the physostome Teleostei, 
and, in addition, the Amiidce, the Leptolepidce, the 
Megaluri, and the Caturi of the Jurassic period. 
„ II. Ganoidei. — Nearly all the recent and extinct Ganoids. 
„ III. Sturiones ( Acipenser , Polyodon) . 
It will be noticed that, in so far as Polyodon and Acipenser are concerned, Lutken 
agrees with H. Muller in regarding them as constituting a group equal in morpho- 
logical value to that in which all the other Ganoids are contained. 
Carus|| retains the Chondrostei as a distinct suborder for the reception of the 
two genera, while the suborder Phractosomata contains the Placodermi and the 
* ‘ Fauna der Vorwelt,’ vol. I., pt. 3. Leipzig, 1848. 
t ‘ Zoologische Briefe,’ vol. II. Frankfurt, 1852. 
+ Mem. Geol. Survey, sec. X. 
§ Vide German translation in ‘ Palmontograpliica,’ Band xxii., 1873. Mag. Nat. Hist. 1871. 
|| ‘Handbueh der Zoologie ’ (Carus und Gerstjicker). 
