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. //. propterygium. me p. mesopterygium. mp. metap- 

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



FIG. 2. 



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



canicula (natural size). 



il. iliac process. /. pubic process, cut across below, bp. basipterygiiun. 

 af. 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. 



