I 5 8 



SELACH11 



TRIBE 2. 



The pectoral fins fuse in front with the sides of the head, and 

 the branchial openings are quite ventral. The rostrum, as a 



FIG. 121. 



Skeleton of Raja balls, L. (From Owen, Anal, of Vertebrates, by permission of Messrs. Long- 

 mans and Co.) 7, scapular region of pectoral girdle ; 8, 9, 10, segments of anterior axiof 

 pectoral fin; 11, posterior axis ; 12, radials of expanded pectoral fin; 10, preorbital process ; 

 52, cartilage plate joining scapula to vertebral column ; 55, posterior outgrowth of pectoral 

 girdle; 63, pelvic girdle ; 68, basipterygium ; c, anterior enlarged radial ; v, pelvic-fin radials. 



rule, is much developed. In this division most of the changes in 

 the skeleton described above (p. 154) are carried out. Extra- 

 branchials are preserved in the Rhinobatidae and in Trygon. The 

 iliac process may be much developed ; since it is large in the 

 Holocephali and in the Tetrapoda, this is possibly a primitive 

 character. 



