82 PRACTICAL ZOOLOGY. 



b. Two projections extending upward, soon uniting 

 to form one spine, the neural spine. 



c. The archway formed above the body of the ver- 

 tebra is the neural arch. 



d. A similar arrangement below, forming the haemal 

 arch and haemal spine. 



Make a drawing of this vertebra as seen from the 

 side ; as seen from the front. 



18. In like manner remove and study a vertebra from a 

 point opposite the centre of the first dorsal fin, with 

 the ribs attached to it. What are the differences 

 between these two vertebrae? 



19. Thoroughly clean the last vertebra, and study care- 

 fully its relations to the caudal fin. 



20. Observe the white spinal cord in the canal formed by 

 the neural arches above the bodies of the vertebrae. 

 This is the nerve-canal, or neural canal; note also 

 the blood-vessels in the corresponding blood-canal, or 

 haemal canal, below. 



THE BRAIN OF THE FISH. 



Cut off the head ; clear away the muscles at the back 

 of the head ; carefully slice off the top of the skull with a 

 strong, sharp knife ; with extreme care cut away the roof 

 of the brain-cavity ; a mass of loose, gray tissue covers the 

 brain, which is of a white or pinkish color ; cautiously 

 pick away this loose tissue, using a small syringe to wash 

 away the loosened matter. Make out the following parts 

 of the brain, beginning at the posterior end : — 



1. The cut-off end of the spinal cord. 



2. The widened part of the spinal cord, where it passes 



