352 
THE OCEAN WORLD. 
The tendency to throw out spines in Spondylus is one of 
striking features. When the whole lower surface adheres to branch^ 
of coral, a very 
fre- 
.th^ 
quent occurrence, 
1 ibB 
are confined to 1 
upper valve, but wh® 0 
a part only of t 
valve, the whole flir 
face becomes covered. 
The shells of the Hammerheads 
leus) have a rough resemblance to * . 
implement from which they derive th el1 
name. The valves are nearly e( l ui . 1 
1, 
the 
Fig. 143. Malleus alba (Lamarck). 
blackish, and somewhat wrinkled on 
exterior, often brilliantly nacred in 
interior. They are enlarged to the 
and left of the hinge, forming prolo°£® 
tions on each side, which give them ^ 
fancied resemblance to the Hammerh e 
At the same time they grow in a direct 10 
opposite to the hinge, which gives s olU ° 
thing approach 10 
the handle of 
implement. , 
This is the & * 
feature which 
glance at 
alia, (Fig. 143) conveys. The 
without teeth, having instead » 
Fig. 144. Malleus vulgaris (Lamarck). 
deep 
conical fossette or dimple, for the reL ^ 
tion of a very strong ligament ' v . g 
acts upon the valves. The anim® ^ 
contained in the interior of th e e 
its mantle fringed by very smftl ^ 
tacular appendages. Only twelve ^ 
tually living species of tbe gencr® 1 ^ 
known, which are inhabitants 0 
Indian Ocean, of the Australian seas, and the Pacific Ocean. 
