334 TEE SEA SHORE 



transparent that the circulation of the blood within the body may 

 be seen under the microscope quite as easily as in the web of 

 the frog's foot and in the tail of the tadpole. 



One very common species of the Blenniidce differs consider- 

 ably in general form from the others, its body being elongated and 

 eel-like, but much compressed laterally. We refer to the Butter- 

 fish or Butter Gunnel (Blennius gunellus), which is often mistaken 

 for a small eel by young sea-side naturalists. It is exceedingly 

 common under stones at low tide, and may be recognised at once 

 by the light rectangular spots along the flattened sides of the body. 

 It is quite as slippery and as difficult to hold as the eel itself. 



It will be interesting to note that the ugly Sea Cat or Wolf- 

 fish (Anarrhichas lupus), which is sometimes sold for food in our 

 large towns, is also a member of the blenny family. It is a power- 

 ful, rapacious fish a veritable wolf of the sea, always ready to 

 attack anything. It feeds on molluscs and crustaceans, the shells 



FIG. 240. THE BDTTERFISH 



of which are easily reduced between the powerful crushing teeth 

 that line the jaws behind the formidable canines. 



The Gobies (Gobiidce) form another interesting family of small 

 littoral fishes, easily distinguished by the fact that the ventral fins 

 are united in such a manner that they enclose a conical cavity. 

 The first portion of the dorsal fin has also six flexible spines. The 

 Spotted Goby (Gobius nvinutus) is commonly to be found on sand- 

 banks, where it is well protected by the colouring of its upper 

 surface, which closely resembles that of the sand on which it rests. 

 It is said to make a nest by cementing fragments together round 

 some little natural hollow, or to utilise an empty shell for a similar 

 purpose, fixing the shell to the surrounding bed, and constructing 

 a tunnel by which it can enter or leave. The eggs are deposited in 

 this nest, and the male keeps guard over the home. The Black or 

 Rock Goby (G. niger) inhabits rocky coasts, clinging to the rocks 

 by means of a sucker formed of the modified pelvic fins. 



