310 THE AQUARIAN NATURALIST. 



The other appendages to each segment are subser- 

 vient to locomotion, and are called the oars ; these 

 are generally two in number, upon each side, one 

 being situated near the back, and the other upon the 

 ventral aspect of the body : the two pairs of oars are 

 generally separated from each other by a wide in- 

 terval, but occasionally they are so nearly approxi- 

 mated as not to be readily distinguishable ; or there 

 are instances in which only one pair is developed. 

 When perfectly formed, each oar is found to consist 

 of a strong fleshy pedicle, from which there projects 

 an appendage called the cirrus, which is of very dif- 

 ferent shape in different genera, sometimes being 

 long and filiform, at others expanded into a broad 

 paddle like that of a Sandwich Islander's canoe, or 

 occasionally it may be very small and scarcely per- 

 ceptible. 



In addition to the cirrus, each fleshy pedicle is 

 furnished with a packet of stiff hairs, which can be 

 protruded or retracted into the body at the will of the 

 animal ; these, from their expansion, add greatly to 

 the propelling power of the oar, and moreover some- 

 times constitute a most formidable apparatus of de- 

 fensive weapons. 



There is no want of locomotive machinery, there- 

 fore, in one of these humble-looking worms : no 

 steamer, with its paddle-wheels at work, presents a 

 spectacle more admirable than that offered by every 

 segment of the Nereis ; and when all combine to beat 

 the waves in unison, the ease and grace with which 

 the creature swims, or rather glides along, almost 

 exceeds belief. 



