LIMBS. 



6l 5 



The pectoral fin. The earliest stage of the pectoral fin 



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 ; /. pubis. 



differs from that of the pelvic fin only in minor points. There 

 is the same longitudinal 

 or basipterygial bar to 

 which the fin-rays are 

 attached, whose position 

 at the base of the fin is 

 clearly seen in the trans- 

 verse section (fig. 346, 

 mpt). In front the bar is 

 continuous with the pec- 

 toral girdle (figs. 344 and 



348). 



The changes which 

 take place in the course of 

 the further development 

 are however very much 

 more considerable in the 

 case of the pectoral than 



in that of the pelvic fin. FlG - 348- PECTORAL FIN OF AN EMBRYO OF 



SCYLLIUM STELLARE. 



By the process spoken Jn ^ nietapterygium (basipterygium of earlier 



stage); inc. p. rudiment of future pro- and meso- 

 pterygium ; sc. cut surface of scapular process ; 

 cr. coracoid process \fr. foramen;/! horny fibres. 



of above, by which the 

 attachment of the pec- 



