518 THE MICROSCOPE. 



The family Cellularia, little-cells, have a curious and 

 wonderful provision of nature for their protection, an 

 operculum, a lid or cover over the apertures of each cell. 

 Cellularia ciliata is parasitical, branching, calcareous, 

 white and tufted ; grows about half an inch in height, and 

 the oblique aperture is armed on the outer edge with four 

 or five long hollow spines. The operculum is pearly, and 

 near the base there is that singular appendage, described 

 as the bird's-head process. Its beauty and transparency 

 render it a favourite object with raicroscopists. 



The Cellularia (now Bugula) avicularia are very accurately 

 described by Mr. Gosse, from his own observations upon 

 specimens secured on the Devonshire coast, during a resi- 

 dence there. He says : "Well does it deserve the name of 

 Bird's-head Coralline, given to it by the illustrious Ellis ; 

 for it presents those curious appendages that resemble vul- 

 tures' heads in great perfection. All my specimens were 

 most thickly studded witli them ; not a cell without its 

 bird's head, and all see-sawing, and snapping, and opening 

 their jaws with the most amusing activity ; and what was 

 marvellous, equally so in one specimen from whose cells 

 all the polypes had died away, as in those in which they 

 were still protruding their lovely bells of tentacles. The 

 stem ascends perpendicularly from a slender base, which is 

 attached to the rock, or to the cells of a Lepralia growing 

 from the rock. The central part of the spine is most ex- 

 panded, the diminution above and below being pretty 

 regular ; during life, the usual colour is a pale buff, but 

 the cells become nearly white in death. When examined 

 microscopically it is, however, that the curious organisa- 

 tion of this zoophyte is discovered, especially when in full 

 health and vigour, with all the beautiful polypes protruded 

 and expanded to the utmost, on the watch for prey. It 

 seems to me as poor a thing to strain one's eyes at a 

 microscope over a dead and dry polypidom, as it does to 

 examine a shrivelled and blackened flower out of a her- 

 barium ; though I know well that both are often indispen- 

 sable for the making out of technical characters. But if 

 you want to get an insight into the structure and functions 

 of these minute animals, or if you would be charmed 

 with the perception of beauty, or delighted with new 



