200 GLAUCUS ; OR, 
Mr. Gosse will tell you more of this marvel, in 
his “ Aquarium,” p. 48. 
Next, your sea-weeds, if they thrive as they ought 
to do, will sow their minute spores in millions 
around them ; and these, as they vegetate, will form 
a green film on the inside of the glass, spoiling 
your prospect: you may rub it off for yourself, if 
you will, with a rag fastened to a stick; but if you 
wish at once to save yourself trouble, and to see 
how all emergencies-in nature are provided for, 
you will set three or four live shells to do it for 
you, and to keep your sub-aqueous lawn close 
mown. 
That last word is no figure of speech. Look 
among the beds of sea-weed for a few of the bright 
yellow or green sea-snails (Nerita), or Conical Tops 
(Trochus), especially that beautiful pink one spotted 
with brown (Ziziphinus), which you are sure to 
find about shaded rock-ledges at dead low tide, and 
put them into your aquarium. For the present, 
they will only nibble the green ulve; but when 
the film of young weed begins to form, you will 
