VERTEBRATA 261 



through the tangle, and the male stands by during incuba- 

 tion, and drives off intruders. 



The same haul of the net which brings forth the little 

 wrasses may very frequently bring to light the " Fifteen- 

 spined Stickleback" (Gasterosteus spinachia). 



This elegant little fish is about five or six inches long. 

 Its colour is dark olive -green, with buff markings on the 

 sides. The under parts are silvery. It has a row of fifteen 

 short spines along the back, which can be raised or de- 

 pressed at will. 



Like its little relative of our inland waters, and its 

 neighbours the wrasses, it builds a nest, but, unlike the 

 last, has some idea of architecture, the nest being usually 

 round or pear-shaped, the weeds of which it is made being 

 laced together with mucilaginous threads. The male keeps 

 guard on the nest and its precious contents, and, like the 

 wrasse, attacks all wanderers that come near. Gasterosteus 

 is shown in the photo (Fig. 112). 



Manv other fishes live and move and have their being 

 in the Zostera fields e.g. the lovely little " one-spotted " 

 and "two-spotted" gobies; the "Mackerel Midge," and the 

 young of the grey gurnards. These last are curious little 

 purple brown fishes, with large side fins, that are re- 

 splendent with purple and blue, a large spot of these tints, 

 that looks just like the " eye " of a peacock's feather, 

 occupying the centre of the large, fanlike fins, making the 

 little fish look like some brilliant, large -bodied exotic 

 butterfly. The gurnards have 'the first few rays of the 

 pelvic fins free that is, they are not joined by membrane. 

 These rays are stout and many pointed. By means of these 

 the gurnard walks, like some huge insect, on the bottom. 



In some sunny pools at low tide little shoals of these, 

 from two to four inches long, may be seen. 



Still in the Zostera pools we find, sometimes abundantly, 

 the curious " Pipe-fishes " (the Syngnathidce). 



