332 THE AQUARIAN NATURALIST. 



retractile, and can be drawn into the interior of the 

 body by the aid of the muscular tube from which they 

 spring. It would be superfluous to point out to the 

 reader the danger which would accrue to the animal 

 itself by the presence of such instruments imbedded 

 in its own flesh, it being evident that by every move- 

 ment of the creature's body they would be inextri- 

 cably forced into the surrounding tissues. The con- 

 trivance to obviate such an accident is as beautiful as 

 it is simple. Every barbed spine is furnished with a 

 smooth, horny sheath, composed of two blades, be- 

 tween which it is lodged ; and these, closing upon the 

 barbs when they are drawn inwards, effectually pro- 

 tect the neighbouring soft parts from laceration. 



Two cartilaginous-looking flexible antenna, about 

 half an inch in length, issue from the head, and a 

 row of peduncles, furnished with stiff setae, borders 

 each side of the body, serving to aid the progress of 

 the animal : nevertheless, when in confinement, its 

 sluggishness is excessive ; it scarcely ever stirs, but 

 always seems in a languid state, remaining nearly in 

 the same position, with the posterior extremity of the 

 body recurved, and discharging a constant stream of 

 water from an orifice near the hinder part of its back 

 with so much force, that a slight vortex is formed in 

 the surrounding water. 



The movements of these Annelides, when they 

 choose to exert themselves, are, however, very swift, 

 half-running, half-swimming ; but they likewise swim 

 with great facility, passing rapidly through the water. 



The Aphrodite most probably preys upon living 

 animals, nor does it spare even its own species. Of 



