154 



MUSCULAR SYSTEM. 



fishes want the feet and their muscular 

 apparatus, and the cyclostome fishes 

 want also the arms and their muscles. 

 The muscular system is greatly relieved 

 in the vertical motions of most fishes 

 by the compression and expansion of 

 their air-sac ; but many of the fiat 

 fishes and the cyclostome species are 

 destitute of this aid, and lie generally 

 at the bottom of the water. The 

 movement of some fishes through the 

 water is aided by a muscular disk in 

 form of a sucker, placed on the back 

 part of the head in the remora, on the 

 fore part of the belly in the lump-suck- 

 er, and around the mouth in the lam- 

 preys, by which they adhere to other 

 animals or bodies moving through the 



water. By the great development of the lateral muscles of the 

 trunk, the saw-fish and the sword-fish are enabled to use 

 their offensive weapons with effect ; the large muscles of 

 the anterior dorsal rays give powerful and varied movements 

 to these parts in the silurus, balistes, lophius, and many 

 other fishes, and the strength of those of the pectoral fins 

 enable the flying-fishes to escape from the water, and to 

 move some hundred times their own length through the 

 air. 



The long compressed trunks of the perenni-branchiate 

 amphibia, as the proteus, the siren, and the axolotl, and of 

 the tadpoles of the higher anurous species, are moved 

 through the water chiefly by the lateral motions of the ver- 

 tebral column and of the tail, as in fishes^ and these motions 

 are effected in the same manner by numerous transverse 

 strata of longitudinal muscular fibres, occupying chiefly the 

 sides of the trunk. These great lateral muscles are still 

 comparatively pale, bloodless, and feeble, and the tendinous 

 intersections of their strata are thin, soft, and delicate. The 

 cellular substance interposed between the muscles of amphi- 

 bia is scanty, of little consistence, colourless, and almost in 

 a semifluid state ; there are yet few tendons connecting the 

 muscles to the soft bones of the skeleton, and there is gene- 



