354 Rev. T. Hincks on British Zoophytes, 



The organ to which I refer bears a striking resemblance to a 

 miniature bird's head, and is mounted on a short pedicle, fur- 

 nished in most cases with a basal joint, by means of which it can 

 be swayed backward and forward. These ' processes ' are dis- 

 tributed in great numbers over the polypidom, one being gene- 

 rally placed on each cell. 



The beaks are continually gaping and closing with much ve- 

 hemence, and the entire organ is frequently swung to and fro. 

 The movements, as it has often been noted, are quite independ- 

 ent of the polypes, and Mr. Darwin has well remarked, that in 

 their functions these bodies (t are related rather to the axis than 

 to any of the polypi." 



There is something very comical in the energy and earnestness 

 with which these tiny jaws open and close, and throw themselves 

 about, no cause being apparent in general for the outrageous 

 gapings and eccentric jerks in which they indulge. They occur 

 on several British species, as for example, Flustra avicularis and 

 Cellularia avicularis. 



While watching on one occasion a piece of the latter zoophyte 

 through the microscope, a worm passed over it and amongst its 

 branches. It was almost immediately firmly grasped by one of 

 the avicularia and forcibly detained. In a short time, one end 

 of it was seized by another, from which, however, by its violent 

 contortions it extricated itself, but not without injury. The first 

 assailant meanwhile kept fast hold, and soon two others caught 

 the unfortunate at different points of the body. Thus it was held 

 securely pinioned, and all its efforts to disengage itself, which, 

 were most vigorous, proved unavailing. The avicularia grasped 

 the body of their victim most viciously, and nearly divided it. 

 When I last observed the contest the worm seemed exhausted by 

 its struggles and scarcely stirred, the beaks remaining firm and 

 motionless. These strange police-officers were very systematic 

 in their operations, and in capturing the intruder seemed to be 

 discharging a very ordinary function. 



There can be little doubt, I think, that it is the office of these 

 organs to defend the Bryozoon from enemies — to arrest creatures 

 or substances which might injure or annoy it. They are well 

 placed for such a purpose, and their incessant gaping and swing- 

 ing must enable them readily to detect the presence of trespassers. 

 The avicularia then must be regarded as part of the machinery 

 of the axis, charged with the special office of keeping the poly- 

 pidom free from extraneous matters. An analogous contrivance 

 occurs on others of the Bryozoa, consisting of long bristles at- 

 tached to the cells by a joint, upon which they move backward 

 and forward with considerable force. These clear away obnox- 

 ious matter from the neighbourhood of the cell, and keep the 



