VERTEBRAL COLUMN 



423 



nioiphosis : the tongue skeleton of the adult (p. 44) represents the 

 hyoid and first branchial arch. 



In addition to the parts of the skull described above there are certain 

 small cartilages of minor importance in relation with the nostrils, 

 spiracle, mouth, and outer sides of the branchial arches (c.j,'., lb and 

 ex. br in Fig. 103). 



The vertebral column has the general character of a 

 jointed tube surrounding the spinal portion of the neural 



nlc 



,/prfor-^"Pn.p 



h.a 



h.cc 



Fici. 104. — -Vertebra; o{ Scyllium canicidn. 



A and K from the trunk, C and D from the middle of the tail ; A and C two 

 vertebra: in longitudinal .section ; B and D single vertebra: viewed from one end. 



b, bony portion of centrum; c. centrum; for. foramen for dorsal, 'Awdi for' . for 

 ventral root of spinal nerve ; h. a. ha:mal arch ; //. c. haemal canal ; //. sp. haemal 

 spine ; i. n.p. interneural plate ; ;/. a. neural arch ; it. c. neural canal ; «./, neural 

 plate ; «. sp. neural spine ; ntc intervertebral substance (remains of notochord) 

 tr.py. transverse process; r. proximal portion of rib. 



canal. Ikying beneath this cavity, />., between it and the 

 coelome, is a longitudinal row of biconcave or aviphiccelous 

 discs, the vertebral centra (Fig. 104, c ) Fig. 108, ai) : they 

 are formed of cartilage, but^have their anterior and posterior 



E E -^^ 



