LIMBS. 



505 



The changes which take place in the course of the further develop- 



///. 



FIG. 347. PELVIC FIN OF A YOUNG MALE EMBRYO OF SCYLLIUM STELLARE. 



bp. basipterygium ; m.o. process of basipterygium continued into clasper ; il. iliac 

 process of pectoral girdle ; pu. pubis. 



ment are however very much more considerable in the case of the 

 pectoral than in that of the pelvic fin. 



By the process spoken of 

 above, by which the attach- 

 ment of the pectoral fin to 

 the body wall becomes short- 

 ened from behind forwards, 

 the basipterygial bar is gra- 

 dually rotated outwards, its 

 anterior end remaining at- 

 tached to the pectoral girdle. 

 In this way this bar comes to 

 form the posterior border of 

 the skeleton of the fin (figs. 

 348 and 349 mp), constituting 

 what Gegenbaur called the 

 metapterygium, and even- 

 tually becomes segmented off 

 from the pectoral girdle,, 

 simply articulating with its 

 hinder edge. 



The plate of cartilage, 

 which is continued outwards 348. PECTORAL FIN OF AN EMBRYO OF SCYL- 



from the basipterygium, or LIUM STELLARE. 



as we may now call it, the m P- metapterygium (basipterygiam of earlier 



17 ,-t r> stage) ; me.p. rudiment of future pro- and rneso- 



metapterygmm, into the fin, pt ^ am ; sc. cut surface of scapular process; 



is not nearly SO completely cr. coracoid process ; /r. foramen ;/. borny fibres. 



