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139 
triangular plates. The edge of each plate is cut very 
regularly into six sharp teeth, which curve in one direc- 
tion, and one other, curved so as to face these. The 
combs stand -side by side, parallel to each other, along the 
whole length of the ribbon ; and there are muscular bands 
or fibres seen affixed to the smaller end of every plate, 
which doubtless give it independent motion. Wo have 
counted one hundred and thirty-six plates on one ribbon ; 
there are two ribbons on each thoracic segment, and there 
are seven such segments ; hence we may compute the 
total number of prehensile comb-like plates to be about 
one thousand nine hundred, each of which is wielded by 
muscles at the will of the animal ; while, as each plate 
carries seven teeth, there arc between thirteen and four- 
teen thousand teeth hooked into the minute cavities and 
roughnesses of the interior surface of the cell, when the 
animal chooses to descend. No wonder, with so many 
muscles wielding so many grappling hooks, that the re- 
treat is so rapidly effected ! 
The bundles of bristles which liue the wart-like feet, 
are very extensively found in this class of animals ; and 
in some species they exhibit strauge and singular forms, 
resembling the fantastic but formidable weapons of some 
semi-savage people. Thus in a flat scaly worm ( Polynoe ), 
common enough under stones at the water’s edge, the 
armoury consists of several sorts of weapons. First, there 
are long lances made like scythe-blades set on a staff, 
with a hook at the tip to capture the fleeing foe, and 
bring him within reach of the blade. Among them are 
others of similar shape, but with the edge cut into deli- 
cate slanting notches, which run along the sides of the 
