THE FRESH-WATER AQUARIUM. 29 
Isopelis fluitans, or the floating Isopelis, is another of 
the curiosities of water botany. It is somewhat common 
in English ponds and slow streams. The blossom is in- 
conspicuous, having no petals; the stamens are three in 
number, and there is but one petal. 
Subularia aquatica is one of the few aquatic plants 
furnished by the great family of crossworts, or plants of 
the cabbage and wall-flower kind. Its common name is 
awl-wort, and suggested by the awl-like foliage which it 
produces under water. It is to be found only in clear 
mountain lakes, for it is a true aquatic alpine, frequent 
only in the North of England, and in Scotland and Ireland. 
The aquarian who resides near any mountain lake or 
pool, should seek for it, and treasure it as the choicest 
gem in his collection. The lower leaves are curve- 
pointed like a cobbler’s awl, and in July it sends up a 
short stalk, bearing a head of snow-white four-petaled 
blossoms, and presents a somewhat unique example of a 
flower in full bloom under the water. My attention was 
first called to this plant by Mr. Dowden’s charming work 
on wild plants, called ‘* Botany of the Bohereens.” 
Ranunculus aquatalis, or the water crowfoot, must be 
known to everyone who has been in the habit of rambling 
in the country quite sober and with eyes open. | It is to 
be found in almost every pond, and by the middle of May 
is in full bloom, continuing gay till far into autumn. Itis 
a member of the buttercup family, and may be recognised 
as a buttercup of a snow white, with a bright yellow 
centre. If you step carefully to the edge of a pond or 
river, where this crow-foot covers the shore-water with its 
