CHAPTER III. 
The Bony Fishes and Ganoids,—S ubclass Teleostomi. 
Formerly the typical bony fishes of the present day were regarded as indicating a 
primary group (Teleostei) of equal rank with a second one known as the Ganoidei; 
the latter containing the American bony pike, and the African bichir, together 
with a host of extinct genera possessing a similar armour of hard ganoid scales. 
A fuller study of these and other allied fossil forms has, however, shown the 
existence of such a complete transition from these so-called ganoids to the typical 
bony fishes that it has become necessary to include the whole of them in a single 
subclass, under the title heading this chapter. Although there is still some degree 
of uncertainty as to the best mode of arranging certain groups of the bony fishes, 
the following scheme may be temporarily adopted:— 
1. Order Actinopterygii —Fan-Finned Group. 
►J 
O • 
o 
m 
f* 
X 
(1) Suborder„ 
( 2 ) „ 
(3) „ 
(4) „ 
(5) „ 
( 6 ) „ 
CO , 
( 8 ) „ 
(9) „ 
f Acanthopterygii —Spine-Finned Fishes. 
Lophobranchii —Tuft-Gilled Fishes. 
Plectognathi —Comb-Gilled Fishes. 
Anacanthini —Soft-Finned Fishes. 
Physostomi —Tube-Bladdered Fishes. 
Isospondyli — Leptolepis. 
AStheospondyli —Bony Pike. 
Protospondyli —Amioids. 
Chondrostei —Sturgeons. 
2. Order Crossopterygii —Fringe-Finned Group. 
In this wide sense the subclass differs broadly from the two preceding ones in 
the structure of the skull, which is formed on what may be termed the hinged type 
( hyostylic ); that is to say, the palato-pterygoid bar remains separated from the 
cranium proper, to the hinder-part of which it is movably articulated by the 
intervention of the hyomandibular. The internal skeleton is more or less ossified, 
with the development of membrane-bones on the jaws; the gill-clefts are but 
slightly separated from one another, and are fully protected by an operculum; the 
membrane-bones of the pectoral girdle (that is to say, the scapula, claviculars, etc.) 
are connected with the hinder-part of the skull; and the external skeleton takes 
the form either of plates of bone or of calcified overlapping scales. In existing 
forms the eggs are small, numerous, and generally massed together; the two optic 
nerves may either simply cross one another, or may give off mutually interlacing 
fibres ; an air-bladder—with or without a duct—is very generally present; and the 
intestine may sometimes be furnished with a spiral valve. 
