1881.] OF THE PAIRED FINS OF ELASMOBRANCHS. 663 



a small zone at the base of the fin, the remainder being formed of 

 a fringe supported by radiately arranged horny fibres ^ 



The true skeleton consists of three basal pieces articulating with the 

 pectoral girdle ; on the outer side of which there is a series of more 



Pectoral fins and girdle of an adult of ScylUum canicula 

 (natural size, Been from behind and above.) 



CO. Coraeoid ; sc. scapula ; pp. propterygium ; mep. mesopterygium ; 

 mp. metapterygium ; fn. part of fin supported by horny fibre. 



Fig. 2. 



Right pelvic fin and part of pelvic girdle of an adult female of Scylliiim 

 canicula- (natural size). 



il. iliac process ; pn. pubic process, cut across below ; bp. basipterygium ; 

 af. anterior cartilaginous fin-ray articulated to pelvic girdle ; fn. part of fin 

 supported by horny fibres. 



or less segmented cartilaginous fin-rays. Of the basal cartilages one 

 (pp) is anterior, a second {mep) is placed in the middle, and a third 

 is posterior {mp). They have been named by Gegenbaur the pro- 



* The horny fibres are niesoblastic products ; they are formed, in the first 

 instance, as extremely delicate fibrils on the inner side of the membrane 

 separating the epiblast from the mesoblast. 



