THE BLACK GOBY. 555 



the fish may have struck them by accident, and not in a deliberate 

 charge. The Sword-fish generally go in pairs. 



The food of this creature is rather varied, consisting of cuttle-fish, 

 especially the squid, and of small fishes, neither of which animals would 

 in any way fall victims to the sword. It certainly has been said that 

 the weapon is used for transfixing the flat fish as they lie on the bed of 

 the sea, but this assertion does not appear to be worthy of credit. 



The young and adult specimens are very different from each other. 

 In the young the body is covered with projecting tubercles, which 

 gradually disappear as it increases in size, and when it has attained 

 the length of three feet they are seldom to be seen. Those on the abdo- 

 men remain longer than the others. The dorsal fin extends in the young 

 specimens from the back of the head to the root of the tail, but the 

 membranes and spines of its centre are so extremely delicate that they 

 are soon rubbed away, and the adult specimen then appears to have 

 two dorsal fins. 



The color of the Sword-fish is bluish black above and silvery white 

 below. The whole body is rough, and the lateral line is almost invis- 

 ible. The usual length of the Sword-fish is from ten to twelve feet, 

 but specimens have been seen which much exceed those dimensions. 

 A few examples of the Sword-fish have been captured in British 

 waters ; one that measured seven feet in length was taken off" Margate. 



We now arrive at the large family of the Gobies, which iucludes 

 many curious fish, and of which the British coasts present many repre- 

 sentatives. 



The Black Goby, sometimes known as the Rock-fish, is a moder- 

 ately common example of the enormous genus to which it belongs, 

 and which contains more than a hundred and fifty authenticated 

 species. The members of this genus may easily be recognized by the 

 peculiar form of the ventral fins, which are united together so as to 

 form a hollow disc, by which they can attach themselves to rocks or 

 stones at pleasure. In fact, this disc, although differing in shape, acts 

 on exactly the same principle as that of the sucking fish. 



The Black Goby prefers the rocky to the sandy coasts, and may be 

 found in the pools left by the retreating tide. Some naturalists deny 

 that the disc is used for adhesion, but I have caught and kept many 

 Gobies, and have frequently seen them sticking to the sides of the 

 vessel in which they were confined. The adhesion was achieved with 

 astonishing rapidity, and the little fish contrived to hold itself with 

 great tenacity. The surface of the Black Goby is very slippery, owing 

 to the abundant mucous secretion which is poured from the appropriate 

 glands ; but after it has been in spirits for some time the edges of the 

 scales begin to project through the mucus, and are exceedingly rough 

 to the touch. 



