700 Marvels of the Universe 
The shells of some of the Rock-borers are further provided with ridges and points, which serve 
as rasps to help in the excavation of the burrow and to file the sides smooth. The Date Mussel 
and the Common Piddock have this characteristic to a marked degree. 
There are two Borers which shouldbe specially mentioned. One is the Flask Shell which, 
besides making a burrow in sandstone, is “ beautifully finished off as though lined with porcelain,”’ 
and covers himself with a jacket composed of odd pieces of stone and sand stuck together by some 
secretion of the mollusc. 
In the background of the illustration on page 697 is shown Magilus, an interesting coral 
dweller of Eastern Seas. This snail is not one of the deeply-boring molluscs. In its younger stages 
it has the habits and shape of the average snail, but as its age increases it seeks a permanent home 
in the coral-reef, and grooves out a little hollow sufficiently large to hold the shell with the 
mouth-piece open at the edge 
to allow the ingress and egress 
of the snail. But the coral 
grows and the snail is compelled 
to extend the limits of his 
cavern if he wishes to preserve 
his communication with the 
outer world ; he therefore adds 
whorl after whorl to the spiral, 
but not symmetrically as do 
most of his brother snails, with 
the result that, as he grows 
older, his shell develops into 
an irregular tube running 
through the coral mass with the 
original small spiral at the end. 
He is forced to continue adding 
to his structure or he would 
soon be completely enveloped 
in a coral grave, so that if he 
is able to survive till he attains 
Photo by a (J.J. Ward, FES. a good age he may have a 
THE NEST OF A MASON-WASP. tube some seven or more inches 
The most curious habit of the Mason-Wasp is its provision for the grub. A 1 H re t ll 
number of grub-cells are here shown, one of which has been broken open to reveal ong. € Canno occupy a 
the caterpillars stored by the mother Wasp for the food of the yet unhatched grub. this long corridor, so he leaves 
the spiral portion and comes out to live in the outer tube and blocks up the disused chambers of 
his home with a solid deposit of lime. 
THE LARGEST WOODPECKER IN THE WORLD 
BY SIR HARRY JOHNSTON, G.C.M.G. 
Tue Woodpeckers are a sub-order of birds of almost world-wide distribution, the only areas of land 
surface from which they are absent being Australasia and the Arctic regions. For the most part 
they are smallish birds, ranging in size from that ofa finch to a jay ; but the example here illustrated 
is almost the size of a crow, the adult being twenty-two inches in length. This form—the 
Imperial Woodpecker—belongs to the group of Ivory-billed Woodpeckers, the white beak 
being very hard and like ivory in appearance. It is a handsomely-coloured bird, mainly black 
