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GANOID FISHES OF THE CARBONIFEROUS FORMATION. 



knowledge, still a matter of some difficulty, especially seeing that, in attempting to 

 co-ordinate fossil with living forms, we are here, as in other departments of Palaeontology, 

 limited to the analogies of the hard parts of the skeleton and the inferences deducible 

 therefrom. The few surviving recent members of the order fall readily into four 

 distinct types— that of Polypterus, of Acipenser, of Lepidosteus, and of Amia. With 

 each of the first three at least there may be co-ordinated an extensive series of fossil 

 forms ; there are others, however, whose systematic position, even to their being retained 

 as Ganoids at all, is still quite uncertain. 



The following arrangement here adopted is based on that of Professor Huxley, who, 

 following up the philosophic researches of Pander, has done more than any other 

 naturalist of recent years to enable us to obtain some insight into the classification of the 

 Ganoids on true morphological principles. 



a. Veri. 



Suborder I. Crossopterygii. — Pectoral, and sometimes also the ventral, fins lobate ; 

 infraclavicular present; rays of dorsal and anal fins frequently exceeding in number their 

 supporting interspinous bones, prseoperculurn extending forward on the cheek ; jugular 

 plates in place of branchiostegal rays ; vertebral column in various stages of develop- 

 ment ; tail heterocercal or diphycercal, sometimes abbreviate-diphycercal ; scales 

 cycloidal or rhomboidal. Including the families Phaneropleurida (?), Holopfychiida, 

 Cyclodipterida, Rhombodipteridce, Ccelacanthida, and Polypterida. 



Suborder II. Acipenseroidei. — Tail completely heterocercal ; notochord persistent ; 

 paired fins not lobate ; infraclavicular present ; rays of dorsal and anal fins exceeding 

 in number their supporting interspinous bones ; prseoperculum, when present, tending to 

 extend forwards over the cheek ; branchiostegal rays in most, but large jugulars in none. 

 Skin in many furnished with osseous scutes or with rhomboidal scales ; in some naked, 

 save on the prolongation of the body along the upper lobe of the caudal fin. Including 

 the families Acipenseridcp, Spatularida, Chondrosteidce, Palaoniscida, Platysomidee. 



Suborder III. Lepidosteoidei. — Tail abbreviately heterocercal ; vertebral column in 

 various stages of development ; paired fins non-lobate ; no infraclavicular ; opercular 

 bones as in Teleostei; branchiostegal rays, with frequently a so-called " median jugular" 

 in front ; rays of dorsal and anal fins corresponding in number to their supporting 

 interspinous bones ; scales rhomboidal, sometimes replaced by angular scutes. Including, 

 besides the recent and somewhat aberrant Lepidosteidcs, a great series of Mesozoic semi- 

 heterocercal forms (Lepidotus, Etcynathus, &c.) not yet satisfactorily limited, or divided 

 into families. 



Suborder IV. Amioidei. — Tail abbreviately heterocercal ; paired fins non-lobate ; 

 no infraclavicular ; opercular bones as in Teleostei ; branchiostegal rays, with median 

 " jugular" in front ; scales thin, cycloidal ; aspect Teleostean-like. Includes the recent 



