Z A. H. H, LATTEY, OBSERVATIONS ON THE POLYZOA, 



Amongst all these creatures, none are more curious than the species 

 of Bugula, called Bugula Avicularia, from its possessing those 

 strange appendages called birds' head processes, and most appro- 

 priately so, from their very exact resemblance to the head and beak 

 of a bird. They are attached to the margins of the cells by means 

 of a footstalk, and each has two " mandibles ;" the upper one fixed 

 and the lower one moveable, just as in birds, and they are opened 

 and shut by powerful muscles wdthin the " head." A most singu- 

 lar and curious sight it is to watch the movements of these "ob- 

 jects" when a portion of the Polyzoary is viewed under an inch or 

 two inch objective, so as to allow a number of these bodies to be in 

 sight at once. It will then be seen that each head keeps up a con- 

 tinual nodding movement, throwing itself slowly back, which its 

 joint-like union to the cell allows, at the same time gradually open- 

 ing its jaws, or rather depressing the lower jaw until the mouth is 

 opened to its full extent, and when the head has gone back as far 

 as it can reach, it suddenly resumes its former position, the mouth 

 closing at the same instant with a sudden snap, and entrapping 

 any luckless animal that may be passing at the time, and then the 

 same proceeding takes place over and over again, without any in- 

 termission. It certainly is a most singular — I might almost say 

 ludicrous — sight to see all the avicularia within the field of the micro- 

 scope practising this perpetual " snapping." The great size and 

 apj)arent strength of the animals which they are capable of seizing 

 and retaining in their grasp, must impress us with a sense of the 

 enormous strength of the muscles which move the jaw, for they 

 seize and retain not only small vermicules, but such large creatures 

 as caprellee, entomostracse, &c. ; and very curious it is to watch the 

 wiithings and struggles of one of these comparatively gigantic vic- 

 tims in its vain efforts to escape from the jaws of its tiny captor. 

 Not unfrequently the captive is seized by another, or even two 

 more avicularise, in other parts of its body, thus making assurance 

 doubly sure, and so deadly is the grip, that I have never seen one of 

 them relax its hold on the application of the medium which is fatal 

 to themselves. 



Various have been the conjectures as to the office of these " heads 

 without bodies," and their exact function in the economy of the ani- 

 mal — some supposing that their office is to protect the delicate 

 creatures over whom they mount guard from the rude contact of 

 foreign bodies which might injure their frail structure ; but many 



