394 



MANUAL OF ZOOLOGY 



SECT. 



portion or all of those of the rest of the fins are slender 

 flexible rods divided into a series of short segments and 

 usually branching at the free ends. In many, however, the 

 anterior portions of the dorsal, ventral and pelvic fins are 

 supported not by flexible jointed rays, but by stiff unjointed 

 sharp spines. 



The paired fins, pectoral and pelvic, are usually thin and 

 flexible, supported mainly, or exclusively, by jointed rays. 

 The pectorals always retain their normal position, just 



UST 



FIG. 220. Salmo fario. Caudal end of vertebral column. ON. centrum; D. F. R. 

 dermal fin-rays ; H. SP. haemal spine ; H. ZYG. haemal zygapophysis ; N. SP. 

 neural spine ; N. ZYG. neural zygapophysis ; DST. urostyle. 



behind the gill-clefts, but the pelvics may become more or 

 less shifted forwards from their typical position beside the 

 vent ; when they are not placed as far forwards as the 

 middle of the abdomen they are said to be abdominal in 

 position ; when further forwards, nearly beneath the pectorals, 

 they are said to be thoracic ; when still further, actually in 

 front of the pectorals and beneath the throat, they are said 

 to \)Q jugular in position. 



A very remarkable deviation from the typical form occurs 

 in the Flat-fishes (Pleuronectidce including the Soles, Plaice, 





