330 THE SEA SHORE 



shown in the accompanying illustration. The commoner ones are 

 known to fishermen and juvenile anglers by quite a variety of local 

 names. 



The family Gobioesocidce contains some small and very prettily 

 coloured fishes of very peculiar habits, known popularly as Sucker- 



Fio. 236. THE RAINBOW WRASS (Labrus julis) 



fishes. They have one or two adhesive suckers between the pelvic 

 fins by which they attach themselves to rocks, stones, and shells. 

 Some are littoral species, and may be searched for at low tide ; but 

 others inhabit deeper water, and are seldom obtained without a 

 dredge. 



One of the former is the Cornish Sucker (Lepadog aster cornu- 

 biensis), which may sometimes be taken in a hand net by scraping 

 the rocks and weeds at low tide on the south-west coast. It has two 

 suckers, each circular in form, surrounded by a firm margin, within 



237. THE CORNISH SUCKER 



which is a soft retractile centre. This central portion is attached to 

 muscles by which it can be withdrawn ; and a vacuum is thus 

 produced, so that the sucker adheres by atmospheric pressure. 

 The structure of the sucking organs can be seen to perfection when 

 the fish attaches itself to the side of a glass aquarium, and if it be 

 taken in the hand it will cling quite firmly to the skin. 



