968 



PISCES. 



other, as those of a chain, and another, which 

 at the will of the fish becomes very moveable 

 or very fixed. We find examples of both these 

 in the family Silurus. 



The articulations with determinate move- 

 ments offer ligaments, cartilaginous surfaces, 

 and a synovial fluid, as in higher animals. 



The articulations between the bodies of the 

 vertebrce are effected by means of a fibro- 

 cartilaginous substance which traverses the 

 bodies, and which sometimes, as in the Stur- 

 geon and the Lamprey, takes the form of a 

 long cord. 



The articulations of the opercular bones be- 

 tween themselves, the pieces composing the 

 branchial apparatus, the bones of the shoulder, 

 of the arm, of the carpus and pelvis, and of 

 the last to the shoulder, are effected by means 

 of interposed fibre-cartilaginous substance. 



Muscular system. The general character of 

 the myology of Fishes has been treated of in a 



preceding article, (MUSCULAR SYSTEM, Comp. 

 Anat.) It will therefore only remain for us 

 in this place to give such an account of 

 their arrangement as the limits of this article 

 permit, dividing them into groups so as to faci- 

 litate reference to the accompanying figures, 

 representing the dissected muscles of the Perch, 

 as described by Cuvier. 



The great lateral muscles on each side of the 

 trunk of the body form a mass that extends 

 from the back of the head and posterior surface 

 of the pectoral zone all the way to the sides of 

 the base of the caudal fin. These two great 

 muscles are divided transversely by aponeurotic 

 laminae into as many layers of fibres as there 

 are vertebrae, giving the flaked appearance to 

 the flesh of Fishes, (fig. 502, f, g, A,) and 

 are connected to all the vertebrae and vertical 

 processes of the spine as well as to the inter- 

 spinous bones. 



Superior and inferior slender muscles of the 



Fig. 502. 



Myology of the Perch. After Cuvier. 



trunk. These are situated in the interspace 

 between the lateral muscles, both along the 

 middle of the back and also of the ventral 

 aspect of the body. 



Proper muscles of the fins. In the caudal 

 fin these are of three kinds, some being super- 

 ficial, others deep-seated, and a third passing 

 from one ray to another. 



In the dorsal and anal fins the arrangement 

 of the proper muscles is very simple, because 

 they are all disposed uniformly, each fin-ray 

 having six, viz. four deep-seated and two su- 

 perficial. 



The superficial muscles are inserted into the 

 fin-ray at its base, one on the right and the 

 other on the left side, and serve to move it in 

 corresponding directions. The deep-seated set 

 (figs 505, 3 and 4) arise from the interspinous 

 bones, and are inserted into the anterior and 

 posterior aspects of the base of the ray, serving 

 to elevate or depress it vertically. 



The movements of the shoulder are effected 

 by the great lateral muscles inserted into them, 

 or by strips derived therefrom. 



The muscles of the pectoral fins (figs. 502, 

 503, 505, 14, 15, and 16) are inserted into the 

 fin-rays, which they serve to elevate or depress 

 at pleasure. 



The muscles of the ventral fins, (fig. 503, 

 17 and 18) arise from the pelvic bone, and serve 

 to expand or advance the fin-rays of the abdo- 

 minal members. 



The muscles of the jaws are represented by a 

 large mass, (fig. 502, 20, 20,) derived from the 

 palato-temporal arch and the anterior edge of 

 the preoperculum, which is inserted into the 

 lower jaw, and serves to close the mouth ; an 

 arrangement very different from that of the 

 temporal and masseter muscles of the higher 

 vertebrata. 



Muscles of the palato-tympanic arch consist 

 of a depressor, (fig. 504, 22,) derived from the 



