POLYZOA. 525 
in fact there is no current between the shell, or siphon, and the wall of the 
tube.” As soon as the animal has completely buried itself it ceases to bur- 
row, and only projects the ends of the siphon from the aperture of the tunnel. 
ALLIED to the preceding molluscs is the SHIPWORM, so called from its 
depredations on the bottoms of ships and all submerged wooden structures ; 
it is found in most seas, and on our own coasts works fearful damage by 
SHIv-WOKM. —( Zeredo nuvaiis.) 
eating into piles, planks, or even loose wood that lies tossing about in 
the ocean. 
When removed from the tube the Shipworm is seen to be a long greyish 
white animal, about one foot in length and half an inch in thickness. At one 
end there is a rounded head, and at the other a forked tail. The curious 
three-lobed valves are seen on the right hand as they appear before being 
separated from the animal. The burrow which the creature forms is either 
wholly or partially lined with shell, and it is worthy of notice that the Ship- 
worm and its mode of burrowing was the object that gave Sir I, Brunel the 
idea of the Thames Tunnel. 
POLYZOA. 
THE very remarkable beings which now come before our notice are appro- 
priately termed PoLyzoa, from two Greek words, signifying “many animals,” 
~ D 
Me 
A. Catenicella lorica. B. Catenicella hastata. C. Catenicella cornuta. 
D. Calpidium ornatum. _E. Salcornaria sarciminnides. F. Cellularia Peachit. 
G. Menipea Fuguensis, (Mouth of a cell.) 
becase a large number of individuals are massed together in groups of 
various forms and textures. 
