4 POLYZOA. 



Many of the genera are furnished with acces- 

 sory organs, which appear to be analogous in 

 office to the pedicellaria of the Starfishes and 

 Urchins. From the remarkable resemblance which 

 (in many species) these appendages bear to the 

 head of a vulture, they have been commonly called 

 " Bird's-head processes" (avicularia). They are 

 usually jointed to some part of the cell, the head 

 moving on the joint freely as on a hinge, nodding 

 to and fro, occasionally opening widely the man- 

 dibles, and closing them with a powerful snap, 

 apparently with great exercise of will and dis- 

 crimination. Ingenuity has been exercised in vain 

 to divine the use of these singular processes, which 

 seem to be so little connected organically with the 

 animal within the cell, that the latter may be quite 

 dead and even decayed away, while the bird's-head 

 maintains its vivacity unimpaired. 



It has long been suspected that these organs 

 are in some way or other useful in the procuring 

 of food, and several observers have noticed the 

 seizure of small roving animals by the pincer-like 

 beaks ; hence it has been too hastily concluded that 

 such victims become the food of the Polyzoan. 

 But it seems to have been forgotten, not only that 

 these organs have no power of passing the prey 

 thus seized to the mouth, but also that this latter 

 is situated at the bottom of a funnel of ciliated 

 tentacles, and is calculated to receive only such 

 minute prey as is drawn within the ciliary vortex. 

 I have ventured to suggest a new explanation. 

 The seizure of a passing animal, and the holding 

 of it in the tenacious grasp until it dies, may 

 be a means of attracting the proper prey to the 

 vicinity of the mouth. The presence of decom- 



