Garden Ponds are a great way to enjoy your California backyard

Snails, Shrimps And Aquarettes Continuing this story of aquarium molluscs we come to the River Limpet, of which two species are indigenous to this country. They resemble the limpet of the seaside in the habit of clinging to a support. This limpet is found, as a rule, clinging to the stems of water lilies. The shell is smooth, not ribbed like the marine species, and is not symmetrical. They are of little value to the aquarist, but are mentioned here because they are interesting to watch in the aquarette.

A small whelk-like mollusc that is fairly common in ditches, etc., all over the country is Succinea. This has an oval, transparent shell with a distinctive amber colouring ; it does not actually live in the water, but disports itself on the leaves of aquatic vegetation. Succinea provides considerable interest in the aquarium.

Most of the freshwater molluscs are dull coloured, though many are delicate in design and structure. An exception is the Zebra Shell, which may be found in most English rivers. They are small and globular and have numerous purple bands or rows of spots by which they can be easily distinguished. The shells are thick and have a deep gloss ; altogether an ideal member for the aquarette. So much for the snail-like molluscs-only a very few of the vast family are noted here ; they may be obtained either by collecting from likely ponds or from the better class dealers. The Fresh Water Mussels, as has been mentioned earlier, by siphoning the water, assist in keeping the water clear. Very few species are to be found in English waters and of these the best are the River Mussel (Unio fluviatilis) and the Swan Mussel (Anodonta cygneus).

These molluscs do not feed as a snail feeds ; they have two tubes or siphons, one of which draws water into the stomach and, after filtering it and so retaining any small organ- isms that may be in the water, ejects it as clear water with the exhalant siphon. Thus, provided there are sufficient mussels to cope with the prolific reproductive powers of the minutiae, the water should be clear eventually.

As they are fairly large, up to six inches in length, they should not be dropped into the pond haphazard, they should be placed on a rake, say, and lowered gently to the desired spot. Moreover, they are very fond of perambulating along the bottom, their mode of progression resembling that of a snow plough. So, if a plant should be in the way, it will be rooted up unless well established-although the mussel has an uncanny way of avoiding obstacles. The mussels, then, should not be placed in the pond until the plants are well rooted.