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ably large ; but the muscles have no tendinous chords, their inser- 

 tions being always fleshy. There are, however, semi-transparent 

 pearly tendons placed between the plates of muscles, which give 

 origin to a series of short muscular fibres, passing nearly at right 

 angles between the surfaces of the adjoining plates. 



The progressive motion of fishes, our author says, is chiefly per- 

 formed by the flexions of the trunk and tail ; the pairs of fins, which 

 some have considered as analogous to feet, being only employed for 

 the purposes of turning, stopping, altering the position of the fish 

 towards the horizon, and keeping the back upwards. The single 

 fins appear to prevent the rolling of the body whilst the tail is em- 

 ployed to impel it forwards. Each of the fins, which are in pairs, 

 is capable of four motions, viz. of flexion and extension, like oars, 

 and of expanding the rays, and closing them. 



Mr. Carlisle now (taking the Cod as a standard of comparison,) 

 describes particularly the mode in which the various motions here 

 spoken of are performed, and then relates some experiments made to 

 determine the effect of the fins on the motions of fishes. For this 

 purpose a number of dace, equal in size, were put into a large vessel 

 of water, and the pectoral fins of one of them being cut off, it was 

 replaced with the others. The result was, that the progressive mo- 

 tion of the fish was not at all impeded ; but its head inclined down- 

 wards ; and when it attempted to ascend, the effort was attended 

 with difficulty. 



From another fish, both the pectoral and abdominal fins were 

 taken. The fish remained at the bottom of the vessel, and could not 

 be made to ascend. Its progressive motion was not perceptibly more 

 slow ; but when the tail acted, the body showed a tendency to roll, 

 and the single fins were widely expanded, as if to counteract this 

 effect. 



From a third fish the single fins were removed. This produced an 

 evident tendency to turn round, and the pectoral fins were kept con- 

 stantly extended, to obviate that motion. 



From a fourth fish all the fins were removed. Its back was kept 

 in a vertical position, whilst at rest, by the expansion of the tail ; but 

 it rolled half round at every attempt to move. 



From a fifth fish the tail was cut off as close to the body as pos- 

 sible. The progressive motion of the fish was considerably impeded, 

 and the flexions of the spine were much increased ; but neither the 

 pectoral nor the abdominal fins seemed to be more actively employed. 



From a sixth fish all the fins and the tail were removed. It re- 

 mained without motion, floating near the surface of the water, with 

 its belly upward. 



The above experiments were repeated on the roach, the gudgeon, 

 and the minnow, with similar results. 



Mr. Carlisle now observes, that the muscles of fishes differ very 



materially in their structure from those of other animals ; that they 



are apparently more homogeneous ; that their fibres are not so much 



fasciculated, but run more parallel to each other, and are always 



p 2 



