32 ZOOTOMY. 



7. The rudimentary ribs (Figs, n and 12, r\ small 

 pieces of cartilage attached to the ends of the transverse 

 processes. 



FIG. 12. Raja nasuta. A trunk vertebra, seen from the front 

 (nat. size). 



c, centrum : i. n, inter-neural plate : n.p, neural process : n.s, neural 

 spine : r, rib : tr, transverse process. 



8. The neural processes ('Figs, n, 12, and 13, n.p), 

 small triangular plates rising one from each side of the 

 dorsal surface of the centrum : a small aperture in each of 

 them transmits the ventral root of a spinal nerve (Fig. 

 n, v.r). 



9. The neural spines (Figs, n, 12, and 13, n.s\ flat 

 plates dividing below into two triangular processes directed 

 outwards, so that the whole plate has, in transverse action, 

 the form of an inverted Y. Each neural spine is situated 

 immediately above the vertebra of which it forms a part, 

 but, save in exceptional cases, is not directly united with 

 the neural processes, so that the neural arch is, so far, 

 incomplete. 



10. The interneural (or intercrural) plates (Figs. 

 ii, 12, and 13, /.), six-sided plates of cartilage, which 

 complete the neural arches laterally, filling up at the same 

 time what would otherwise be the intervertebral foramina. 

 Each transmits the dorsal root of a spinal nerve (Fig. n, 

 d.r), the ventral root of which traverses the neural process 

 next in front. 



