THE STING- RAY. 



Text-figure 3. 



435 



~d. 



1 ojL. 



Trygon pastinaca. 



Lateral view of spine, with diagrammatic sections at A, B. 



c. Canals, d. tooth, g. glandular tissue, i.s.e. invagination of specialised 



epithelium, m.v.r. median ventral ridge, p.l. pigment-layer. 



Text-figure 4. 



Trygon pastinaca. 



Half-section of spine separating from tail, showing invagination of specialised 

 epithelium and pigment-layer. 



c. Cartilage, d.m.s. dentate margin of spine, e.t. ordinary epithelium of tail, 

 m.f.t. muscle-fibres of tail, o.p.s. osseous portion of spine. s.e.i. special 

 epithelium of invagination, t.g. tissue of groove, t.t. tendon of tail. 



