TEREDO-RESISTIXG RIVER WORKS. 
753 
The designer cannot make too many studies ; but there is one 
thing to be guarded against, and that is being encumbered by them. 
The road to success being by the rule, never design with either Nature 
or your studies before you, the actual thing being not malleable 
enough for use ; but study well your subject and studies ; then, putting 
them aside, you will find that your impressions adapt themselves w r ith 
surprising case to your purpose. Make studies continually, for, inso- 
much as invention or design is little more than a new combination of 
those images which have been gathered and deposited in the memory, 
it is evident that a great part of every designer’s life must be 
employed in collecting materials for the exercise of his genius. 
Nothing can come of nothing; he who has not laid up materials 
cannot produce combinations. 
I will now draw my paper to a close, not because I have 
exhausted the subject, for I find it vast as it is interesting, but for 
fear of wearying those of my hearers who may be less interested in it 
than myself. 
5.--TEREDO-RESISTING RIVER WORKS. 
By THOMAS PARKER , C.E., Rockhampton , Queensland. 
THE TEREDO. 
The name locally given to the Teredo is the Cobra; in other 
localities it is commonly know as the ship-worm. Its place and work 
in the economy of Nature appear to be that of a river and sea scavenger, 
and it performs a useful work generally in clearing away the large 
quantities of drifting timbers in the rivers and seas, especially of warm 
climates, as this timber, if not destroyed, w'ould otherwise accumulate 
in large quantities and choke up the waterways. 
The following description of the animal is from L. Eiguier: — - 
“The singular acephalous mollusc, known to naturalists as the Teredo , 
has the appearance of a long worm without articulations. Between 
the valves of a little shell, with which it is provided anteriorly, may be 
seen a sort of smooth rim, which surrounds a swelling projecting pad 
or cushion. This cushion is the only part of the body of the animal 
which can be regarded as a foot. Starting from this point, all the 
body of the Teredo is enveloped by the shell and mantle, the latter of 
which forms a sort of sheath communicating by two siphons with the 
exterior. The Teredo lays a spherical greenish egg. Shortly after 
fecundation these eggs are hatched. At first naked and motionless, 
these larva? are soon covered with vibratile cilia, when they begin to 
move, at first bv a revolving pirouette, afterwards swimming about 
freely in the water. When one of these larvae has found a piece of 
submerged wood, without which it probably could not live, the curious 
spectacle is observed of a being which fabricates, step by step and as 
it requires them, the organs necessary for the performance of its 
functions. It begins by creeping along the surface of the wood by 
means of the very long tubes with which it is furnished. Then it is 
observed from time to time to shut the valves of the little embryo 
shell which partly envelopes it. As soon as it has found a part of the 
