OF THE PAIRED FINS OF ELASMOBRANCHS. 



723 



of the fin is the base, where is it attached to the side of the body. 

 The cartilaginous skeleton only occupies a small zone at the base 

 of the fin, the remainder being formed of a fringe supported by 

 radiately arranged horny fibres 1 . 



FIG. i. 



Pectoral fins and girdle of an adult of Scyllium canicula (natural size, 



seen from behind and above). 



co. Coracoid. sc. scapula, pp. propterygium. me p. mesopterygium. mp. metap- 

 terygium. fn. part of fin supported by horny fibre. 



FIG. 2. 



JJTL 



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



canmila (natural size). 



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

 a/, anterior cartilaginous fin-ray articulated to pelvic girdle, fn. part of fin supported 

 by horny fibres. 



1 The horny fibres are mesoblastic 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. 



