346 THE LIVING ANIMALS OL THE WORLD 
Of the Scallops many of 
the larger species are highly 
esteemed for the table. It is 
notable of them that they can 
progress through the water 
in a jerky, flight-like manner 
by the repeated flapping of 
their opposing shells. In 
many scallops the jewel-like 
eyes are developed in a row 
round the margin of the 
mantle. 
The Bivalve Class in- 
cludes certain representatives 
which are held in evil repute, on account of their destructive habits. PnOLAS and its allies 
bore their way into solid rock, bringing about its complete disintegration. From the dreaded 
Ship-worm, or Teredo, on the other hand, there would appear to be no description of wood 
that can withstand its ravages. 
The Bivah^e Molluscs are not without fresh-water representatives. The well-known PoxD- 
and River-mussels, which form the most conspicuous examples of this group, number several 
hundred species. While insipid and of no account for the human commissariat, many of its 
members produce pearls of value. One such, obtained from the river Conway, in North Wales, 
is said to occupy a place in the crown of England. 
The Chitons, or Multivalve Molluscs, invite brief notice. As the last-named title 
implies, the shell-elements in this group are relatively numerous, consisting of eight pieces, 
or plates, which may form contiguous transverse shelly shields that entirely cover in and 
protect the dorsal surface of the elongate, boat-shaped body, or may be more or less isolated 
from one another. In the former instance the animal bears some considerable resemblance to 
a gigantic limbless wood louse, and, like that familiar terrestrial crustacean, it is capable of 
rolling itself into a spheroidal shape as a means of protection. None of the chitons are 
provided with eyes in the adult state in that region of their body — namely, the head — where 
they might be most naturally expected to exist. Recent scientific investigation has, however, 
elicited the fact that in various species the respective shell-plates are studded with minute 
eye-specks, the aggregate number of visual organs thus possessed by certain forms reaching to 
the astonishing figures of 1 1 ,000 or 12,000. The majority of the chitons are shallow-water, 
rock-frequenting molluscs, which may be successfully sought by turning over stones at low 
water. 
CHAPTER II 
LAMP-SHELLS 
A LITTLE group of double-shelled creatures, formerly regarded as near allies of the Oysters 
and Mussels, are the Lamp-SHELLS. Their scientific appellation, signifying “ arm-footed,” 
relates to the two spirally convoluted arm-like structures which constitute the salient 
features in these animals. That of lamp-shells bears reference to the small circular perforation 
near the extremity, or “ beak,” of the united shells, which imparts to the entire structure a 
not altogether remote resemblance to an ancient Greek or Roman lamp with its sub-terminal 
wick-hole. In all essential points of their organisation the lamp-shells differ so essentially 
from ordinary bivalves that they are now generally recognised as representing an independent 
animal class, having, as a matter of fact, a closer relationship with Worms than with Molluscs. 
In their earlier condition certain lamp-shells are indistinguishable from larval worms; while 
the convoluted arms of the adult animals, thickly beset with bristles and hairs, closely resemble 
Ph^iD IV. Saville-Kent^ [Milford-. n^Sea 
A QUEENSLAND OYSTER-BANK 
Illustrating another characteristic groivth-phase of the Australian rock-oyster 
