MICBOSCOPE AT THE SEA-SIDE. 75 



and elevated above the surface of the object on 

 which they are placed, as in the case of Bowerbankia, 

 seen at 156. A beautiful form of these creatures 

 is the shepherd's-purse coral (Notamia bursaria), 

 represented at figure 157. This creature belongs 

 to a group of the polyzoa, remarkable for possess- 

 ing little processes on the margins of their cells, in 

 shape resembling the bowls of tobacco-pipes, birds' 

 bills, and bristle- like organs. On examining them 

 with the Microscope, they present a very compli- 

 cated organization. The birds' bills possess two 

 jaw-like processes, which open and shut like a bird's 

 beak, and from this fact they have been called avicu- 

 Icvria, or bird's-head processes (a). The tobacco-pipe 

 form in Notamia is peculiar to that genus. In 

 other species, as in Bugula avicularia, seen in 

 figure 158, these creatures possess not only the 

 bird's-head process, but a second, consisting of a 

 long bristle or seta, attached by a joint to a process 

 below (a). These bodies are called vibracula, and 

 the bristle-like extremity is kept constantly in 

 action, and the form of avicularia is seen in Bugula 

 Murrayana, at figure 159. Both processes are seen 

 in Scrupularia scruposa, at figure 160. Few objects 

 are more curious under the Microscope than these 

 avicularia and vibracula in a state of action. 

 Whilst the function of the vibracula, seen at a, 

 figure 160, seems to be to sweep away objects 

 that would interfere with the life of the animal in 

 the cell, it has been suggested by some that the 

 avicularia secure by their jaws the food necessary for 

 its sustenance : it seems probable, however, that 

 they serve the purpose of a protective police. Of 

 the various forms which the cup itself assumes, 

 none are more interesting than those of the snake- 

 head zoophyte, shown at figure 161, plate 6, in 

 which it assumes the form of a snake's head, with 



