130 



FIRST LES80KS m ZOOLOGY. 



wide, we see that the jaws are armed with namerous fine 

 teeth, as are also the bony projections on the sides and roof 

 of the mouth; the teeth are seen to be sharp, conical, and 

 curved backwards, so that the jaws can retain a slippery fish 

 in their grasp. 



The shape and arrangement of the scales should also be 

 noted, as well as the "lateral line" (Figs. 137, ins; 139, L). 



Fie. 137. — The minnow and its intemsil structure. A: 71, nose; gc, gill cover; af, 

 pectoral or arm fin; i/,leg-fln or ventrals; df, dorsal fln;fl^, anal fin; cf, caudal 

 fin; ms. mucous scales of the lateral line. B: n, nose-pit; e, eye-nerre; ea, 

 ear-nerve leading from the brain; g, gills; 7i, heart; i, oesophagus; s, stomach; 

 k, Mdney; v, vent; da, dorsal artery; a, air-bladder; 6, backbone; nv, nerve 

 cord or spinal cord. 



A well-prepared skeleton of a perch (Fig. 138) or cod 

 should then be studied. The chief point of interest is the 

 spinal or vertebral column, which consists of vertebrae. 



From each vertebra arises a dorsal or spinous process (g), 

 and a similar process below called the " haemal spine" (e). 

 These form the support of the dorsal, anal, and caudal fins. 

 The spinal cord or nerve passes from_ the brain through the 



