39° 



MANUAL OF ZOOLOGY 



may be nearly completely cartilaginous {Hexanchus and 

 Heptanchits), but usually the centra are strengthened by 



t>a s. br % 



Fig. 233. —Skeleton of sting-ray (Urolophus testaceus), ventral view, a.v.fi, 

 anterior vertebral plate; has, br, basi-branchial plate; br.i-br.j, branchial 

 arches The branchial rays are represented as having been removed, the round 

 dots indicate their articulations with the arches cl % skeleton of clasper; h. in, 

 hyomandibular; ky, hyoid arch; lab, labial cartilage; lig, ligament connecting 

 the hyomandibular with the palato-quadrate and Meckel's cartilage; nick, 

 Meckel's cartilage; ms. pt, mesopterygmm; mi pt, metapterygium of pectoral 

 fin; mi.pt', metapterygium of pelvic fin; nas, nasal cartilage; pal, palato- 

 quadrate ; pect, pectoral arch ; pi, pelvic arch ; pro.pt, propterygium ; sp, spiracu- 

 lar cartilage. 



