MUSCULAR SYSTEM OF FISHES. 169 



along the interspaces of the dorsal fins in the Cod : similar muscles 

 extend from the last dorsal to the caudal fin {u) in the Perch ; and 

 ' infra-carinales' (v) extend from the anal to the caudal along the keel 

 of the tail. In the Gymnotus the supra-carinales form a single pair, 

 Avliich extends from the occiput to the end of the tail. The mo- 

 dified cranio-dermal spines, which constitute the oval sucking-disc of 

 the Remora, have a complex series of minute muscles, which raise or 

 depress the transverse lattice-work ; and thus become the means of 

 giving the little feeble fish all the advantage of the rapid course of 

 the whale or the ship to which it may have attached itself. The 

 muscular and membranous webs of the coalesced pectorals and 

 ventrals of the Lump-fish, form a sucker on the opposite surface of 

 the body, by which it may safely anchor itself to the rock, in the 

 midst of the turbulent surf or storm-tossed breaker. 



The muscles of the gills, the eyeball, the air-bladder, and other 

 special organs will be described with the parts they move. 



The muscular tissue (myonine) of fishes is usually colourless, often 

 opaline, or yellowish ; white when boiled : the muscles of the pectoral 

 fins of the Sturgeon and Shark are, however, deeper coloured than 

 the others ; and most of the muscles of the Tunny are red, like those 

 of the warm-blooded classes. The want of colour relates to the com- 

 paratively small proportion of red blood circulated through the 

 muscular system* ; and to the smaller proportion of red-particles in 

 the blood of fishes : the exceptions cited seem to depend on increased 

 circulation with great energy of action ; and, in the Bonito and Tunny, 

 with a greater quantity of blood and a higher temperature f than in 

 other fishes. The deep orange colour of the flesh of the Salmon and 

 Char depends on a peculiar oil diffused through the cellular sheaths 

 of the fibres. The muscular fasciculi of Fishes are usually short and 

 simple : and very rarely converge to be insei'ted by tendinous chords.| 

 The proportion of myonine is greater in fishes than in other Ver- 

 tebrata ; the irritability of its fibres is considerable, and is long 

 retained. Fishermen take advantage of this property, and induce 

 rigid muscular contraction, long after the usual signs of life have 

 disappeared, by transverse cuts and immersion of the muscles in cold 

 water : this operation, by which tlie firmness and specific gravity of 

 the muscular tissue are increased, is called ' crimping.' 



There are many and great modifications of the muscular system of 

 Fishes, especially in the aberrant orders at the two extremes of the 

 class : Carus has illustrated some of these in the Plagiostomes (xLiil. 



* XLviii. pp. 4. 16. ft. i xux. p. 3. 



