REPTILES, MOLLUSKS, AND INSECTS.
The lower orders of creation supply many interesting specimens for the
aquarium. Among the reptiles--newts, or water lizards, and the common
frog, may be recommended as offering some forms of positive elegance,
and some habits worthy of observation. The smooth newt, the warty newt,
and the noble triton, are almost essential to the completion of the
collection, and as they respire air at the surface, they do not exhaust
the water of oxygen. The beautiful markings on the belly, and the
graceful motions of these strange creatures, are sure to afford
entertainment to those who can overcome the very common repugnance felt
towards such creatures.
Some of the mollusks commend themselves for their beauty, and will be
prized by the aquarian enthusiast. Among the univalves, lymnea, physæ,
planorbis, and paludina, are the most useful and ornamental. I must
caution the amateur against the too ready adoption of any species of
lymnea; they are destructive, and particularly fond of _Vallisneria_,
_Stratoides_, and _Callitriche_, and while they are the best of
cleaners, they are also the most indiscriminate of gluttons.
_Paludina Vivipara_ is a handsome snail, with a bronze tinted, globular
shell; but _Planorbis Corneus_ and _carrinatus_ are still handsomer,
having a spiral form, resembling the horn of a ram. These latter are to
be trusted anywhere; they are good cleaners, and seldom attack the
plants. Water snails breed rapidly in tanks, but the carp devour the
young as fast as they appear; hence it is advisable to remove the spawn
into jars containing healthy plants, such as _Callitriche_, in which
they may remain for observation of growth, till stout enough to be
committed to the tank.
[Illustration: PLANORBIS CORNEUS, PALUDINA VIVIPARA, LYMNEA STAGNALIS,
UNIO PICTORUM, TUMIDUS, & ANODON CYGNEUS.]
Among the bivalves, the fresh-water swan mussel, _Anodon cygneus_, and
the Duck mussel, _Unio pictorum_, are interesting burrowers, and perform
a great service in the tank. They act as scavengers, not by the process
of eating off objectionable growths, as in the case of univalves, but by
the straining off of matters held in suspension in the water, and
filtering it in a pure state, by the mechanism of their syphons, and
ciliated gills. It is very interesting to watch them thus engaged, and
to note the force of the stream which they project from time to time.
The only creature of the insect kind that I can recommend for general
adoption is the caddis worm, a comical and interesting creature, that
can never mar the beauty of the tank. Half-a-dozen may be thrown in, and
searched for occasionally--the search will always be well rewarded. When
the cad closes his hybernacle, it will be desirable to remove it to a
jar, to obtain a better opportunity of witnessing the transformation of
the dormant worm into a four-winged fly of Stephens's family of
Phryganea.