194 A NKW ZEALAND NATURALIST'S CALENDAR. 



heads out to see what is going on in the outside world. 

 The sea -slugs are usually very brightly coloured, and 

 are really most elegant creatures when seen in the pools, 

 with their pearly white or clear lemon-yellow bodies and 

 their beautifully plumose gills. They are so conspicuous 

 that we must suppose that they are not very good eating, 

 otherwise they would be quickly decimated. Sea-anemones 

 of many hues and sizes often line the cracks between 

 the rocks in the pools, opening out their wide tentacles like 

 the petals of a cactus. If we drop a worm or a bit of meat 

 into the centre of the flower the arms close rapidly and 

 engulf the morsel. 



One reason why pools on a rock-bound coast are so 

 interesting is no doubt the constant element of change 

 which they manifest. Not only are the objects very 

 numerous, and often very peculiar, but there are con- 

 stantly new forms appearing, and the variety is infinite. 

 It is this unceasing changefulness of aspect which makes 

 the sea itself so interesting, and which keeps one from 

 wearying when contemplating its protean moods. 



No reference to Moeraki would be complete which 

 omitted to notice its boulders. These singular spherical 

 masses of rock really lie on the beach half way to 

 Hampden. They are not so numerous now as they were 

 a score of years ago, the smaller ones having been con- 

 stantly carried away as curiosities or mementos. Some 

 of them may be seen fractured by the action of the sea. 

 They are found to contain cavities lined with crystals of 

 calcite or calcium carbonate. Geologically these singular 

 stones are known as septaria, and they are concretionary 

 structures derived from the blue sandy clay which here 

 forms the predominant rock. The formation is a sedi- 

 mentary one, and is, of course, quite different from the 

 volcanic rock of which the headland is formed. As their 

 scientific interest is great, it is fortunate that there are 

 still many of these boulders left, and of such size that 

 no collector, however enthusiastic he may be, or how- 

 ever destructive his propensities, can succeed in doing away 

 with them. 



