1 3 o 



ELASMOBRANCHII 



fold is produced at its hinder margin into an outstanding lobe. The 

 basipterygium is continued backwards into this lobe as a cartilage 

 rod, consisting, as a rule, of two short anterior and one long 

 posterior segment. A dorsal groove carrying the skin with it is 



FIG. 89. 



Raja Wanda, Holt. Dorsal view ; the cartilaginous skeleton has been completely exposed 

 on the right side, a, b, c, d, /, cartilages of clasper ; a.l, anterior lobe of pelvic fin ; 



basipterygium ; cZ, clasper ; ej>, covering- plate ; i.p, iliac process ; o.s, opening of sac ; p, pelvic 

 girdle ; p.p, prepubic process ; pr.r, enlarged preaxial radial ; pt, posterior preaxial radial ; *, 

 dotted line indicating ventral glandular sac ; st, second segment of basipterygial axis ; sty, 



developed along this terminal piece, which becomes hollowed out to 

 receive it. The edges of the cartilage are rolled round so as almost 

 completely to enclose the groove in a split tube open at both ends 

 (Fig. 88). Spermatozoa may pass in at the front and out at the 

 hind end. The internal tegumentary tube projects forward as a 

 blind sac, and from its wall develops a special gland. The main 



