20 THE SEA-SIDE AND AQUARIUM. 



sides of the tank, rendering it to a certain degree 

 opaque. This is a healthy symptom of the vitality of 

 its occupants, but, as it has the disadvantage of 

 seriously obscuring your view of the interior, you 

 will be desirous to remove it. That can easily be 

 done by rubbing the surface of the tank with a bit of 

 rag, twisted round the forefinger, or, better still, tied 

 to a rod. There is a yet easier way of attaining the 

 desired result, and that is, to introduce a number of 

 Periwinkles and Limpets. These animals very soon 

 give obvious tokens of how greatly pleased they are 

 at being transferred to such an accessible range of 

 tender pasturage. They eat away with a relish truly 

 astonishing. It is indeed an interesting sight to 

 notice a Buckie thus engaged. I have often sat for 

 half an hour at a time, watching through a hand-lens 

 the busy molluscous mower. Mr Gosse, describing the 

 operation, says in his usual happy style, " When he " 

 (the Periwinkle) " eats, he separates two little fleshy 

 lips, and the glistering, glass-like tongue is seen, or 

 rather the rounded extremity of a band of it, rapidly 

 running round, like an endless land in some piece of 

 machinery, only that the tooth points as they run by 

 remind one rather of a watch wheel ; for in an instant 

 this appears, then the lips close again and presently 

 re-open, and the tongue again performs its rasping. 

 It is wonderful to see ; perhaps " (adds this amiable 

 author) " not more wonderful than any other of God's 

 great works, never less great than when minutely 

 great ; but the action and the instrument, the perfect 



