VERTEBRATA: FISHES. 



46; 



so-called " median " fins by being always disposed in pairs, 

 usually symmetrically. Hence they are often spoken of as the 

 paired fins. 



The scapular arch (figs. 250, 251) supporting the pectoral limbs is usually 

 joined to the skull (occipital bone), and consists of the following pieces on 



co 



Fig. 251. Pectoral limbs of Fishes (after Owen). A, Cod (Morrhita -vidgaris) : B, 

 Angler (Lophius). ss Supra-scapula ; j Scapula ; co Coracoid ; r Radius ; Ulna ; 

 cc Carpal bones ; f Fin-rays, representing the metacarpus and phalanges of the 

 fingers. 



each side : I. The supra-scapula (ss) ; 2. The scapula (s), articulating 

 with the former ; and, 3. The coracoid (co), attached above with the 

 scapula, and united below, by ligament or suture, with the coracoid of the 

 opposite side, thus completing the pectoral arch. Lastly, there is often 

 another bone, sometimes single, but oftener of two pieces, attached to the 

 upper end of the coracoid, and this is believed to represent the collar-bone 

 or clavicle. * 



* These are the views entertained by Owen as to the composition and 

 nature of the pectoral arch of fishes ; but they are dissented from by Mr 

 Parker, one of the greatest living authorities on this subject. 



