3756 The Zoologist — November, 1873. 



of an invisible pipe B 2, and into apartment i by means of an 

 invisible pipe c 2. The flow of the water after being pumped into 

 tanks 9 and 10 is caused simply by gravitation, there being a fall 

 of from three to six inches from tank to tank ; thus in tanks 9 and 

 10 the water stands at a height of six feet, while in tanks 1 and 18 a 

 it is only three feet. Yet this constant flow Mr. Lloyd considers 

 still insuSicient for the supply of oxygen to all the inmates; he 

 has therefore arranged a number of small pipes, one for each tank, 

 with a nipple nearly touching the surface of the water, and through 

 each of these water is forced in a small but powerful stream : in its 

 short passage between the nipple and the surface of the water each 

 of these streams entangles and incorporates a great quantity of air, 

 so that myriads of bubbles of air are driven with great force, but 

 in a state of subdivision so fine as to resemble steam or falling 

 sand, almost or quite to the bottom of each tank, whence they 

 return and reascend to the surface with a gentle and deliberate 

 movement strangely contrasting with the violence of the descent. 

 This forcing in of the air corresponds as nearly as possible with 

 what takes place in the ocean when lashed into foam by the violence 

 of the winds ; the waves tumbling tumultuously one over another 

 entangle and carry with them by their proverbial violence a vast 

 quantity of air, which, after being dashed downwards, again rises 

 to the surface, having discharged its office of communicating purity 

 to the water and life-supporting breath to its inhabitants. 



It appears from a paragraph at page 9 of Mr. Lloyd's ' Hand- 

 book,' that he places more reliance on the effects of vegetation 

 than his admirable arrangements for aeration and circulation, just 

 described and explained, would have led us to suppose ; neverthe- 

 less " if all the necessary vegetation of the Crystal Palace Aquarium 

 could be gathered together, it would, when deprived of water, 

 j)robably not weigh one ounce": these are Mr. Lloyd's own 

 words ; but the passage to which I desire to invite attention is the 

 following : — 



" Towards the close of the [last] ceutury, namely in 1790, the late 

 Sir John Graham Dalyell began to keep living marine animals for obseiTa- 

 tiou, in bis bouse in Edinburgh ; and continued this practice till bis death, 

 about 1850; but be changed the sea-water two or three times a week, 

 though some of the animals hved for eight or ten years ; 'and one sea 

 anemone (Actinia Mcscmlnjanthemum), taken by him from the sea iu 



