432 
THE OCEAN WORLD. 
| 
and T)c Blainville, species which furnished the true Tyrian purple 0 
the ancients ; but our space prevents us from dwelling on them. 
The Tritons are ranged beside the genus Mar ex in the system 
Their shell is irregularly covered with scattered swelling excrescence 
not, as in Murex, in longitudinal rows, but scattered all over tb 1 
Fig. 284. Cerithiura 
aluco (Linnaeus). 
Fig. 285. Cerithium giganteum 
(Lamarck). 
surface. About forty species of Triton are known. They 1°^^ 
every sea, but more especially those in warm countries. Triton ^ 
riegatum, vulgarly called the Marine Trumpet (Fig. 280), is a ^ 
large shell, which even attains a length of sixteen inches ; it is enam® ^ 
with great elegance, in white, red, and tawny-brown. They come 
the Indian Ocean, where they are very common. Triton iotoi t 
