MAEINE VEETEBBATES 



331 



This peculiar Little fish is only about three inches long, and its 

 broad head is marked with two conspicuous purple spots, with a 

 blue dot in the centre, and surrounded by a yellowish ring. 



The allied species include the very small Two-spotted Sucker 

 (L. bimaculatus), which is of a bright red colour, and adheres to 

 stones and shells in deep water ; the Sea Snail (Cyclopterus 

 liparis), about four or five inches long, with a soft and slimy 

 semi-transparent body; and Montagu's sucker (C. Montagui), 

 which is usually under three inches in length, and may be dis- 

 tinguished by its peculiar habit _ 

 of curling the body laterally 

 when at rest. 



Equally interesting are the 

 little Sticklebacks (family Gas- 

 trosteidce), the fresh- water repre- 

 sentatives of which are known 

 to almost everyone. Their 

 pugnacious habits, the bright 

 colours assumed during the 

 breeding season, and the won- 

 derful nests which they build 

 for the protection of their eggs 

 and young, have all served to 

 make them popular with those 

 who take interest in the forms 

 and ways of animals. They 

 are, moreover, such hardy crea- 

 tures that they may be kept 

 alive for a considerable time in 

 any well-managed aquarium. 



In this family the hindmost 



portion of the dorsal fin is soft-rayed, but the front portion is re- 

 presented by a row of strong, sharp, erectile spines, which constitute 

 a formidable weapon of offence and defence. Most of the species 

 live in fresh water, but all the members of the family seem 

 to be able to live almost equally well in both salt and fresh 

 water. 



We have one marine species the Sea Stickleback or Fifteen- 

 spined Stickleback (Gastrosteus spinachia), which may be caught 

 on rocky and weedy coasts. It derives one of its popular names 

 from the presence of fifteen spines along the middle of the back. 



Fia. 238. THE FIFTEEN-SPIKED 

 STICKLEBACK AND NEST 



