C6 SUPPLEMENT ON 



THE MYOLOGY OF FISHES. 



The spinal vertebra), united by cartilages, are enabled to 

 move upon each other with greater facility to the right and 

 left, in one or more curves, alternately convex and concave, 

 than vertically, where the superior and inferior spinous pro- 

 cesses, more or less lengthened, interpose. It is therefore by 

 alternately striking the water with the trunk and tail, that 

 fish chiefly move forward, the pectoral fins operating as regu- 

 lators, and the ventrals both like oars and feet ; both pairs 

 assist in ascending or descending, in which operation the 

 swimming bladder, placed under the spine, is commonly the 

 chief agent, being acted upon by the compression of the ribs 

 or otherwise, as the intended motion may require. This 

 purpose is effected by means of muscles, which in fish are, as 

 in other vertebrated classes, composed of fleshy fibres, more 

 or less red, and of tendinous fibres, white or silvery respec- 

 tively, in similar positions. 



The chief of these are the pair of great lateral muscles, 

 extending from the head and shoulders to the base of the 

 caudal fin, representing the three bundles of the sacro-spinal, 

 in a very complicated form, but without indicating the dis- 

 tinctions of cervical, dorsal, and caudal, as in other animals. 

 They are separated from each other by the spine and its pro- 

 cesses, by the deep muscles of the interspinous bones, and by 

 the abdominal cavity. Their fibres are transversely divided 

 by aponeurotic bars, into as many successive strata as there 

 are vertebra). These when boiled offer the division in flakes 

 observed in fishes. They are placed obliquely to the spine, 

 in such a manner that their superior and inferior por- 

 tions are directed the one forward and upward, the other 

 forward and downward, while the centre parts form an 

 arch with the convexity directed forward. The muscle is 



