Fig. 5. 
Fig. 6. 
Fig. 7. 
Fig. 8. 
Warte. — Plexi of Necturus. 
PLATE 2. 
Diagram of plexus of both sides in a specimen bearing asymmetrical sa- 
cral ribs on vertebra 19 and 20. 
Diagram of plexus of both sides of a specimen bearing asymmetrical sa- 
cral ribs on vertebra 18 and 19. 
Diagram showing a bifurcate transverse process and sacral rib. 
Diagram of sacrum of a specimen with a supernumerary sacral rib on one 
side. 
