THE COD. 105 



94. The median fins, thin vertical folds of integument 

 supported by bony fin-rays (§ 19) ; three of them are dorsal 

 in position (dorsal fins, Fig. 30, d.f. i, d.f. 2, d.f. 3), ex- 

 tending from immediately behind the head to the tail ; two 

 are ventral (anal fins, a.f. i, a.f. 2), extending between 

 the urinary aperture and the tail ; and one is posterior, the 

 caudal fin {c.f) ; the latter is apparently quite symmetrical 

 (homocercal), its rays being equally distributed above and 

 below the fleshy lobe in which the tail ends. 



95. The pectoral fins (fore-limbs) (Fig. 2,/./), situated 

 on each side of the anterior region of the trunk, close behind 

 the gill-slits, and about midway between the dorsal and ventral 

 contours. The shoulder girdle to which they are attached 

 (§§ 70 — 74) can be felt immediately behind the gill-slit. If 

 the pectoral fin be made to stand out at right angles to the 

 body, it will be seen to have a dorsal surface looking 

 upwards and backwards, a ventral surface, downwards 

 and forwards, a strong, straight pre-axial border towards 

 the head, and a thin curved post-axial border towards the 

 tail. When left to itself, it lies with its dorsal surface against 

 the side of the body and its pre-axial border looking upwards. 



()(). The pelvic or so-called ventral fins (hind-limbs) 

 {pv.f), small fins situated below and slightly in front of the 

 pectorals : the pelvic girdle (§77) to which they are attached 

 can be felt in the angle between the ventral ends of the 

 shoulder girdles. The surfaces and borders of the pelvic 

 fins have the same names as those of the pectorals, and are 

 easily identified. 



XVII. ' Carefully dissect away the skin from the left 

 side of the body, observing the following : — 



1 The following sections (§ XVII— 99) may be omitted until after the 

 dissection of the viscera, and then worked out on the right side of the 

 bjdy. 



