76 
Tanks No. 6, 24 and 26. 
which are themselves well protected, as for example by the possession 
of defensive weapons or poisons. Thus some flies have adopted the 
appearance of bees or wasps, and many butterflies perfectly innocuous 
themselves, resemble very closely other butterflies which are very distasteful 
to insect-eating animals. This interesting phenomenon termed "Mimicry” 
has been observed in marine animals of almost every class. It affords a 
most convincing proof of the correctness of the theory according to which 
gradual changes in animal and vegetable forms are brought about by a 
natural selection of the forms most fitted to survive. — Scorpaena has 
poisonous rays in its dorsal fin, but it is not such a dangerous animal as 
the Sting-fish. A large species, of red colour and with curious eyes, 
Scorpaena serofa, will be seen in tank No. 6. 
Allied in habit to the Sea-scorpion is the Goby, Gobius (Fig. 130), 
a small, dark, ground-loving fish always to be seen at the bottom of tank 
No. 26, generally hidden in a crevice of the rock or in a bunch of algae, 
but more fond of movement than Scorpaena. Under natural conditions 
in the spawning season they leave these hiding places and construct a 
chamber covered in by the roots of the sea-weeds, where they lay their 
eggs. The male fish is the architect of the nest, as is the case with the 
Sticklebacks. At the entrance to the nest he waits to entice females into it, 
and fertilizes the eggs as soon as they are laid. Then he protects the spawn 
for about two months and wards off most courageously all enemies. If a large 
number of females visit the nest, he enlarges it and provides it with several 
exits; this has also been observed in the Aquarium on some occasions. 
The numerous species of the Blennies, Blennius, are small, very 
agile, predatory fishes which live in large troops in those parts of the 
coasts, which are covered with sea-weeds. Their mobile bodies are 
continuously darting about and, should danger threaten , they disappear 
at once into some hiding place. Their curiosity and "cheek” is extra¬ 
ordinary, and causes them to snap at everything, and to annoy whatever 
cannot protect itself. They nibble off the gills of the tubicolous worms, 
they make dashes for the eyes of crabs and fishes, and they worry the 
ascidians till the latter die. So they go on with all helpless animals. The 
finest and largest form is the Butterfly-fish, Blennius ocellaris (Fig. 131), 
which possesses a large black eye-like spot on each side of its dorsal fin. 
It will be found in tank No. 26. 
Hidden away similarly among the rocks we find the Rockling, Mo- 
tella (Fig. 132, tank 24), which belongs to the family of the Cods. 
