240 Journal of Comparative Neurology. 



of the first spinal, though it apparently also receives a few 

 fibres from the r. ventralis of the second spinal. It con- 

 sumes probably all of the motor fibres of the r. ventralis 

 c. The levator muscle of the pectoral fin is supplied 

 chiefly by the r. ventralis b of the first spinal, but partly 

 by the r. ventralis of the second spinal. The skin of the 

 pectoral fin is supplied by three branches ; the dorsal part 

 by a nerve which comes from the ventral ramus of the 

 second spinal and includes all of the sensory fibres of that 

 ramus; the middle part by a nerve which in one case 

 comes from the ventral ramus of the third spinal, in 

 another case from the ventral rami of both the second 

 and the third spinals ; the ventral part by a nerve which 

 comes from the ventral ramus of the third spinal. 



The composition of the brachial plexus may be tabu- 

 lated as follows: 



First spinal nerve. 

 Ramus ventralis, b, 



Sensory: supplies all of the sensory fibres of the r. 



cervicalis. 

 Motor: supplies all of the motor fibres of the r. 

 cervicalis (for the m. sterno-hyoideus) and 

 most of those for the levator of the pectoral fin. 

 Ramus ventralis, c^ 



Sensory: supplies all of the fibres for the nerve for 

 the skin between the pectoral fin and the oper- 

 cular cleft. 

 Motor: supplies almost all of the fibres for the de- 

 pressor of the pectoral fin. 



Second spinal nerve, r. ventralis, 



Sensory: supplies dorsal part of pectoral fin and 

 sometimes the middle part. 



