334 FISHES. 



In the carp, these communications take place by exceedingly fine 

 threads.* 



The second of these nerves ( s ) is that which unites with a branch 

 of the fifth pair, to form the dorsal nerve, (©) of which we have 

 already spoken. 



The branch (?) which gives twigs to the diaphragm, comes also 

 from the nerve of the eighth pair. 



The last of the nerves of the cranium, comes from the medulla 

 oblongata, after the eigth pair ; it gives a branch to the natatory 

 bladder, after which its main trunk is distributed to the anterior part 

 of the shoulder, going as far as the muscles, which extend from the 

 humerus to the os hyoides ; but branches are sent off from it to anas- 

 tomose with the first spinal, and this plexus forms the trunk from 

 which the nerves of the external muscles of the pectoral fin, and 

 those of its anterior surface proceed. 



The second spinal pair ( w ) gives nerves to the interior muscles, 

 and posterior surface of this same fin. 



In the tringles, this pair is remarkable from the size it assumes in 

 coming out of the ventebral canal, and from the large branches which 

 it gives to the free rays, placed in these under the pectoral fin. It 

 arises in this fish at the side of the last of the five pairs of tubercles 

 which follow the cerebellum in the singular organization of this 

 genus. 



In fishes whose pelvis is suspended from the bones of the shoulder, 

 whether their ventrals come out in front of the pectorals or under 

 them, or behind, the ventrals derive their nerves from the third and 

 fourth spinaJ pairs ; the third supplies their muscles attached to the 

 pelvis ; the fourth supplies them also, but it is for the most part dis- 

 tributed to their rays : these muscles also receive some twigs from 

 the fifth. 



In the fishes called jugular, whose ventrals are attached farther 

 forwards than the pectorals, these nerves ai'e curved below to reach 

 the parts under the throat for which they are destined ; but they arise 

 from the same pairs. 



This is not the case with the fishes called abdominal. The nerves 

 which supply their ventrals come from more distant pairs. In the 

 carp, they are furnished from the seventh and eighth spinal pairs. 



* M. Weber has thought, that it was a character proper to the dorsal nerve to 

 receive twigs from the spinal nerves ; but the lateral nerve from the eighth pair, 

 receives twigs from them also in a great many fishes, and probably this will be 

 found to be the case in all. 



Plate IV (in ©) exhibits a part of the dorsal nerve formed by the fifth and eighth 

 pair, before it dips down under the small lateral muscles of the rays, and (in jf ) the 

 superficial nerve from the eighth pair, which runs under the lateral line. We have 

 represented in pi. V, the dorsal nerve (in 0) throughout its entire extent, with the 

 filaments it receives from all the nerve-; of the spine; and the deep seated lateral 

 nerve {tot it) of the eighth pair, which passing under the appendices of the ribs, 

 also receives filaments from all the spinal nerves, and goes to its termination in a 

 plexus on the side of the end of the tail. The branch of the first, which, in the cod 

 for instance, follows the base of the anal, could not be shown because we could not 

 find it in the perch. 



