MARINE VERTEBBATES 333 



weeds in almost every rock pool, and under stones as they await the 

 return of the tide. Their bodies are generally cylindrical, and are 

 either naked or covered with very minute scales. The dorsal fin 

 runs along the whole length of the back, and each pelvic has one 

 spine and two soft rays. When taken out of the water the gill- 

 cavities widen considerably, and the eyeballs will be seen to move 

 independently of each other, like those of the chamaeleon. 



Most of the blennies are very active and voracious fishes, often 

 giving considerable trouble to the angler when fishing with a rod 

 among the rocks. They will bite at almost anything that moves, 

 and, completely swallowing the angler's hook, will immediately 

 rush into a crevice from which it is often difficult to remove them. 



Most of them have tentacles on the head by which they assist 

 their movements among the rocks and stones ; and some actually 

 creep up the rugged surfaces of rocks by means of their ventral 



FIG. 239. THE SMOOTH BLENNY 



fins. They can all live for a long time out of the water, being able 

 to retain a supply of water in their expanded gill-chambers to keep 

 the gills moist. 



The Smooth Blenny or Shanny (Blennius pholis) is one of the 

 commonest species. It reaches a length of four or five inches, and 

 has no tentacles on the head. The Eyed Blenny or Butterfly 

 Blenny (B. ocellatus) may be distinguished by the conspicuous 

 spot on the spinous portion of the dorsal fin. The Large Blenny 

 (B. gattorugine) inhabits deeper water, chiefly off the south-west 

 coast, and reaches a length of a foot or more. The Crested Blenny 

 (B. cristatus) is named from the small crest on the head which can 

 be raised and depressed ; and the Viviparous Blenny (Zoarces 

 viviparus), as its name implies, brings forth its young alive. 

 The last species often exceeds a foot in length, and is found princi- 

 pally on the north and east coasts. The newly-born young are so 



