2 26 Journal of Comparative Neurology. 



between that muscle and the dorsal musculature, the 

 second behind the insertion of the depressor, and both 

 distributing to the surface of the fin. Their ramuli run 

 out parallel with the fin rays, those of the first branch 

 supplying the skin of the middle portion of the fin, those 

 of the second branch the skin of the ventral portion. 



The third branch is the true ventral ramus, containing 

 all of the motor fibres and the remainder of the sensory 

 fibres. Having separated ventrally from the other 

 branches, it receives a small coarse-fibred twig from the 

 brachial plexus, then continues ventrad to supply the 

 ventral musculature {v. m.) and the skin lying immediately 

 behind the pectoral girdle. The three branches of the 

 ventral ramus are crossed externally near the point of 

 their separation by the other fibres for the pectoral fin 

 derived from the brachial plexus ; but the third spinal has 

 no connection with the brachial plexus save the small 

 motor twig received by the ventral ramus, though on the 

 opposite side of the specimen plotted the relations are 

 somewhat different ; seethe account of the second spinal. 



III.— The Second Spinal Nerve. 



The roots of the second spinal nerve are larger than 

 those of any of the succeeding nerves, the dorsal root 

 {d. 2) being somewhat larger than the ventral. The two 

 roots pass out through a common foramen in the neural 

 arch of the first free vertebra. The two dorsal rami are 

 like those of the third spinal nerve; the ramiis medius 

 (r. in. 2) also has the same relations except that it appears 

 to contain only motor fibres. 



The large ventral ramus [r. v. 2) under the lateral edge 

 of the dorsal musculature is joined by a large bundle of 

 coarse and fine fibres from the mixed ventral ramus of the 



