Family =Amiidae=. Amia--bow-fin. Order 4. TELEOSTEI. Suborder (1). PLECTOGNATHI. Family =Balistidae=. Balistes--file-fish. Family =Gymnodontidae=. Diodon--globe-fish. Family =Ostracionidae=. Ostracion--coffer-fish. Suborder (2). PHYSOSTOMI. Family =Siluridae=.--cat-fishes. Family =Cyprinidae=. Cyprinus--carp. Family =Esocidae=. Esox--pike. Family =Salmonidae=. Salmo--salmon. Family =Clupeidae=. Clupeus--herring. Exocaetus--'flying fish'. Family =Muraenidae=. Anguilla--eel. Suborder (3). ANACANTHINI. Family =Gadidae=. Gadus--cod, haddock, whiting. Family =Pleuronectidae=. Solea--sole. Suborder (4). PHARYNGOGNATHI. Family =Labridae=. Labrus--wrasse. Scarus--parrot fish. Suborder (5). ACANTHOPTERYGII. Family =Cataphracti=. Dactylopterus--flying gurnard. Family =Percidae=. Perca--perch. Order 5. DIPNOI. Suborder (1). SIRENOIDEI. Family =Dipteridae=. _Dipterus._ Family =Monopneumona=. Ceratodus--barramunda. Family =Dipneumona=. Protopterus--African mud-fish. Lepidosiren. Suborder (2). ARTHRODIRA. Family =Coccosteidae=. _Coccosteus._ _Dinichthys._ NOTE. Palaeontological research has disclosed the existence of a great number of forms which seem to connect with one another almost all the orders of fishes as usually recognised. Forms connecting the living Ganoids with the Teleosteans have been especially numerous, so that these terms Ganoid and Teleostean can hardly be any longer used in a precise and scientific sense. This has rendered the subject of the classification of fishes a very difficult one. Though unsuitable for adoption in a work like the present, by far the most natural classification hitherto proposed seems to be that of Smith Woodward[15]. He considers that the course of development of fishes has followed two distinct lines, the autostylic and hyostylic (see p. 119), and groups the various forms as follows: HYOSTYLIC. AUTOSTYLIC. Subclass 1. ELASMOBRANCHII. Subclass 3. HOLOCEPHALI. 1. Ichthyotomi. 1. (unknown). 2. Selachii. 2. Chimaeroidei. 3. Acanthodii. 3. (unknown). Subclass 2. TELEOSTOMI. Subclass 4. DIPNOI. 1. Crossopterygii (Palaeozoic 1. Sirenoidei. and Mesozoic). 2. Crossopterygii (Cainozoic). 2. (unknown). 3. Actinopterygii. 3. Arthrodira. The primitive forms in each of these four subclasses have the fins archipterygia (see p. 127). CLASS II. AMPHIBIA. Order 1. URODELA. Suborder (1). ICHTHYOIDEA.