PLATE I. 



Fig. 1. Section through an anterior dorsal vertebra of a specimen 12.5 c. ra 

 long, showing the three pairs of cartilaginous rays penetrating to the notochord, viz., 

 the cartilages which support the bases of the upper arches, the bases of the lower 

 arches, and the aortal supports. 



Fig. 2. Ventral view of the 3(5th dorsal vertebra of adult specimen, showing 

 especially the gaps in the bone which are occupied by the cartilaginous aortal sup- 

 ports. 



Fig. 3. Ventral view of 13th and 14th dorsal vertebrae of adult. 



Fig. 4. Ventral view of 1st and 2nd dorsal vertebrae of adult. 



Fig. 5. Section of penultimate dorsal vertebra of specimen 12.5 c. m. long. 



Fig 6. Section of last dorsal vertebra of same specimen as the last. Taken 

 near the middle of the vertebral centrum. 



